Fiancé dislikes my adult children

Who adds more to your life at this stage?
Who is likely to bring you joy and contentedness in the future?

May I suggest that you change your mind about actually getting married. My OH and I are very much committed to each other but won't be getting married because the law states that our assets then would be joint.
I want what I have to go to my offspring as does he. By choosing not to marry we have removed a possible barrier to them accepting a new partner for their parent. You never know what resentments they might be harbouring.

When I read your second post I'm siding more with your fiancé .
If your kids have free access to your house and contact you when they want something - then , they aren't really there for you .

Is their intense dislike of him anything to do with inheritance ?

I watched one of my oldest friends through the years of misery and loneliness and then , almost abandon her new boyfriend because her teenage son didn't like him .
This new boyfriend was her first love and a very nice man .
I remember her son as a very sulky little boy .
Of course , he too had been abandoned by his father , but now despite having a life of his own - he was determined to ruin the new relationship .

I think that your kids shouldn't have the keys to your house .

If this man is going to make you happy - you have to make a stand .
Or is he trying to control you ?

At the moment , you are on an emotional see saw .
Maybe it's time to have a break if things cannot be resolved peacefully .
It doesn't have to be permanent .

Wishing you luck for the future .

I would have to show him the door after the "snake's" comment it does not bode well at all with me.
His comments about them having a door key makes me feel he will become more controlling in the future my AC's all have a door key for emergencies since I have been on my own and it gives me peace of mind,if your family stop visiting you just think how lonely you will be in the future its just not worth it is it.

Foghorn……. They are her children even as adults and he should be supporting her in getting the adult children to toe the line not just by laying down the law. Abuse starts small and grows

What a difficult situation for you. I think that you would be wise to ask for relationship counselling with your fiancé so you can both work out some boundaries with your adult children that suit you both. Within that Counselling you may find out why your children don't like your new partner or you might find he is a keeper who is just struggling with the situation and expressing himself badly.

My husband has always found my daughter difficult as she was the one who consistently and persistently made explosive shock waves throughout the family with her behaviour. Whilst the nub of what he was saying about her wasn't unfair, the way he expressed it actually really hurt me. We did Family Therapy and it helped to a small degree but eventually I had to put my foot down. He could think what he liked but I expected him to be civil to and about her. Gradually everything settled down and the only time he says anything is to warn me that something I might say to my daughter is likely to bounce back and bite me where it hurts. Most times he's right!

On reflection agree with Glorianny.

Is he funny with your friends and extended family too? Mine was and I ended up trapped with him in his lifestyle.. no friends and family thought I didn’t want them around as I was so quiet.

If not the think about what you want, maybe he is or isn’t right but you are questioning things already.