Any advice for helping my situation

Silly question, but does she know that what she is saying is classed as 'rude behaviour'?

Why not try this tack:
Adult: Your hair looks lovely. Did Mummy do it up for you?
Child: What's it to do with you? Mind your own business.
Adult: Do you know what - I'm very interested to hear why you've asked me to mind my own business. Tell me what it means, and how exactly to do this.
Child: This, that, this that etc.
Adult: You've asked what's it to do with me. Well, I'll tell you but first, you tell me why you think it's NOT to do with me.

I'm simplyfying it, of course but my point is that the child may not comprehend why it's rude. As an example, why is it rude to put our elbows on the table? "It just is" may satisfy an adult but not a child.

Far better to teach her the correct language to use, so that the next time, her response would be in line with, "I'd rather not say" instead of "Mind your own business".

(I know that she is able to behave better with granddad but perhaps he has taught her the acceptable terminology?)

Speak to her, tell her its not acceptable. Speak to her parents ask them to talk to her. And your husband could also let her know its not acceptable. I probably wouldn't be that tolerant with her she old enough to understand not to treat you like that.

Granjenny, I really feel for you, personally I think this type of behaviour should be nipped in the bud, your husband seems to be enjoying the situation. I know my youngest two grandchildren (5 yrs & 3 yrs) whilst loving their Grandad are more fond of me, despite the fact I will take no more bad behaviour from them than I would have done from their Mummy - she fortunately agrees. Two weeks ago the 5 year old spoke to me rudely, I automatically said “how dare you speak to me like that”, he went white, and apologised immediately. I know it will happen again from time to time, he is just 5 yrs old and learning, his parents and I are determined he will learn the right way. I hope you get this resolved very soon, despite the fact that we love them to distraction they deserve to be brought up with boundaries.

I'm amazed that the OP's DH hasn't already stepped in to support his wife!
I disagree with inishowen - showing one's vulnerability in the face of this behaviour is definitely not the way to go. It could encourage the child to capitalise on her rudeness.

I agree with Welbeck, your OH needs to be pulling her up! In fact, when she is trying to start conversation with him, he should be saying "mind your own business " when she tells him how much she loves him, he should be saying " what do you want?"

She is clearly playing people against each other and that's not right.

The very fact that her parents don't pull her up either speaks volumes of their lack of respect for you too!

I certainly think that your husband should say something to her. Even if he wasn't in the same room at the time and didn't hear her (which I guess happens) , he could take her on one side and say that he was very upset to hear her being rude to you and it's not nice when people are horrible to other people is it?
Similar thing happened with my parents and one of my nieces - she was like an angel to my dad, but to my mum, to not put too fine a point on it, she was a spiteful little ***!
My dad just had a word while my mum was out and it never happened again!

When our children were born we agreed we’d always support each other when dealing with them - even if later we discussed it and had differing views on how we should have gone about it. We never had these discussions in front of them.
We agreed same over GC, if rude/badly behaved to one of us we present a united front on how unacceptable it it is - don’t put up with this bad behaviour but get your husband on side immediately, he should be backing you up, as should the parents.

I agree with Bluebelle. Get your husband to step in and let her know it is not acceptable to talk to you like this. Any adults in her life who are not telling her this are giving her the message that it is ok. That's not fair on you, or her. If she loves her Grandad so much, it almost sounds like she might be jealous of you. So he needs to make it clear how important you both are to him.

She’s trying it on and needs to be told calmly, quietly, but firmly by you that you consider she is being rude and that it is not appropriate to speak to other people in that way. You are entitled to your view about what constitutes appropriate and mutually respectful behaviour and to voice it. I doubt very much you would dream of speaking to her in such a manner and am saddened that you haven’t had more support from your DH or daughter.

I dont know why the child treats you this way. Could you get her on her own and ask her? Maybe appeal to her better nature and say that every time she is rude to you it really hurts your feelings. Tell her you often feel like crying, and how would she feel if one of her family treated her this way. Good luck.

Just tell her that if she continues to be rude she can’t come to your home any more, and granddad should say the same.

I agree with everyone who says your H should say something to her Grannyjenny, and if it happens in front of her parents and they don't say anything, have a quiet word with them and say you're no longer happy having her to stay.

I do agree in many instances that ignoring the bad and responding to the good is the way to go, but not in this case.

Why doesn't her beloved grandfather say 'Don't speak to Grannie like that' and then walk away from her?

I agree with Luckygirl your granddaughter is old enough to be told that this is unacceptable.
Don't make a big issue of it but do be clear that this is rude and she needs to apologise. Your husband should be clear about it too.

Two options: ignore or pick her up on it as rude.

At her age I think it is appropriate for her to be told clearly that this is rude.

I think both of you should say that it is not acceptable: "That is rude, please do not speak like that again."; but then move quickly on without making a major issue of it.

I do think that you need to detach your emotions from this. It should not make you feel "non-existent" - you are the grown-up here and you need to stand back and recognise that it is just a phase and your role (jointly) is to help her in her growing up and know what is right and what is wrong. And if she sees you getting emotional about it she will do it all the more.

I think your DD is wrong to say ignore it completely. If any of my GC (even the younger ones) spoke to me like that their parents would be very clear with them that this is not acceptable. They would require that they apologise.

If this is her attitude at eight, and assuming there are no underlying problems causing the behaviour what will she be like at ten? This needs to be stopped. Do you ever look after her for her parents to go out? If so, I would refuse until they speak to their daughter. They don’t appear to be positive role models do they?

I know that if one of my grandchildren spoke to me like that, there is no way my daughters or SiLs would sit back and let it happen. She’s 8 years old, not a baby or toddler. I’d just ignore her and tell your husband to stop being such a wuss. He’s in the ideal position, as flavour of the month, to have a kind word in her shell-like

I really don’t think this is one of those occasions where you apply ignore the bad and praise the good.

Her parents are telling her it’s ok to speak to you that way by not challenging her in the moment. I would be utterly shocked to hear any child speak to someone that way in front of their parents and not be challenged.

She is acting like a brat and her behaviour needs addressing by you and. Your husband jointly but primarily by her lazy parents!

It sounds like she's jealous of you and is trying to monopolise your husband. I can't see why or how an eight year old can make you feel non-existent though? She's certainly touching a nerve.
I think grandad needs to pull her up over her behaviour and tell her she's being rude and it's not acceptable. She'll "mind" about that and it'll sink in more than if you say it.
He must realise her behaviour isn't acceptable surely? Does he want a rude granddaughter?

No child should be called a little brat she may be displaying brattish behaviour but that shouldn’t define her jayt
It may be a stage she’s going through I definitely think Granddad is you lynch pin here as she adores him so much if he was to reprimand her and say ‘Darling don’t speak to Nanny like that it’s very unkind and I m sure you won’t want me to think you’re an unkind girl’ that’s all, no more details needed then if it happens again repeat it again etc
You can’t make a child love you but you can make sure they treat you with respect and 8 is not too young to learn that lessson. She won’t want to upset granddad
I think her parents are very much in the wrong how will she learn the right way to respect people if they just ignore it
If my grandkids had spoken to me like that my daughter would have said “don’t talk to Nan like that”
By the way is it new behaviour or has she always shown you disrespect ?

It's up to Grandpa to step in when this happens and explain that her behaviour to Gran isn't acceptable and has to stop. It definitely shouldn't be allowed to continue as it's not right and it's not nice either.

I have every empathy with Granjenny and you must be upset by this rudeness although I agree with another poster that said at age 8 they are testing boundaries and must be pushed back so they learn better behaviour.

I too felt upset about one of my G.Ds who sometimes has tantrums. She is 7 and half years old and when her mother was talking to me on the phone last week the child got into a temper. The child was shouting loudly and called me some
abusive swear words. I told her to see to the child and rang off. I rang back later and asked the childs mother to put her on the phone to apologize. I was told she is quiet now so she did not want to upset her. I did not visit them on the weekend as I am still upset about the swearing and the fact that the childs mother did nothing to reprimand her.

I’m with Furret on this. She sounds like a little brat and, if I were you, Granjenny, I’d tell her so in front of her parents. If they don’t like it just tell them their child needs controlling and it’s high time they had a serious chat with her about how she treats you. She won’t get far in life behaving like that.

Offering a slightly different perspective here. We had a bit of a rough time with my youngest and my mum around this age as she was having issues realising that he wasn’t a wee boy anymore and he had opinions of his own. I had to take mum aside and ask her to stop babying him as he hated it - whereas his papa (my dad) didn’t do the coochie-coo voice or cut up his food or constantly tell him to be careful - he spoke to him like a little human.
Now in no way does that excuse rudeness - but are you maybe communicating with your GC at a younger level?
As for completely ignoring her as has been suggested here, please do not play psychological games with a child, it’s cruel, unnecessary and IMO emotionally abusive.
Maybe get DH on board to say something - or have you asked him if he’s noticed anything you’re doing that could have caused this. This isn’t me laying blame, but if it’s something simple you can change then why wouldn’t you?

She’d get the sharp end of my tongue for sure. And I think your DH needs to stop lapping up the adoration and tell her not to speak to grandma like that.