How would you deal with this…..

He should tell the children, they will learn from someone else or worse still outside the family. What the dickens is the matter with him?

I actually think that it's seriouslyweird not telling his teenage children that he's remarrying.
Only the OP can decide what she wants to do, but I wouldn't attend the wedding if he wasn't prepared to tell the children first.
I'd go once he'd told them; possibly they wouldn't like it but I'd consider that to be my son's and his new wife's problem.

If he has truly 50/50 custody how does he expect to keep this secret?

What a horrible, selfish father those poor boys have. If I were the grandma I definitely wouldn’t go to the wedding, it would show that I approved of the deceit and I would feel so disloyal to the grandchildren and be unable to enjoy the day.
On a practical note won’t there be new clothes around the house, cards and won’t the new love have a ring ? At the boys age, they don’t miss a thing and will surely know if not already then very, very soon.
If I was the boys mum I would attempt to get full custody as the very new ex is behaving in a cruel and dishonest way, it seems that he doesn’t consider or respect his children's feelings.
I feel so sorry for you too being in this situation,

I agree with those who say the remarriage may be too soon, why the rush? If his children have only just become reconciled to the new woman then it's common sense to let the present situation continue to improve until the children are happier and more accustomed to this.
They've been through a major upheaval already and will feel justifiably (imo) upset if this marriage goes ahead so soon and then takes place behind their backs! They'll find out sooner or later, far better they are told about it from the beginning and not on the grapevine.

I would tell my son that I will not attend the wedding unless his children are told. He seems spineless

Retread

I would gently point out to my son that he might later, regret not having included the children, as it will come out that he has married is girlfriend. What I mean is - he may regret the message that is being sent by excluding them from this happy occasion.

I don't think I'd tell him 'gently'. I think I'd tell him in no uncertain terms that getting married behind his children's backs is plain wrong. What does he plan - to do the deed while they're at school and they arrive home to the new situation? They may not be happy with the prospect of him getting married, but they're going to have to know at some point surely, so why not be honest about it and give them time to live with the realities of having a stepmother?

I wonder how the prospective new wife feels about their marriage being kept secret from his children ...

You DS needs to tell his children and include them or he risks losing them. Why wouldn't he?!

Where will his new wife live when they are married? If they share childcare 50/50 won't the children find it rather odd to suddenly have someone sharing the house with them.. He's being very short sighted not getting his children on board... if they were properly included they might just accept her..

Spot on easybee, If the sons children are becoming acceptive of the girlfriend they should all give it more time. Where’s the rush? The son is showing a great disregard for his children which is to his shame. Could it be that the girlfriend is the instigator of this situation for her own benefit? Also as one other comment suggests the notion that ‘ Children are very adaptable’ makes my blood boil the pain of being estranged from one’s biological parents never goes away. Granny your son is weak time to make him take responsibility and man up!
I applaud you for your concern for your grandchildren please don’t be complicit in your son’s plans. Whatever the reason for the divorce/re-marriage the grandchildren will need you more than ever to be their anchor. I wish you all well.

OmG.is your son for real,? Feel sorry for children and you in this absurd stupid situation you are in

In your place, I would decline the wedding invitation and tell my son clearly that much as I accept he is in love and wishes to marry this woman, and I am happy for him and hope to meet her, but I cannot accept that he is not at least telling his teenage children of his decision. So I would not attend and at least be able to tell my grandchildren that I did not approve of their father's not telling them, he was getting married again.

Is he really intending to march into the house with his new wife and blithely say, "Hi kids, NN and I got married this morning"?

He and his new wife may well be hurt or offended if you follow my suggestion, but if you go to the wedding your grandchildren will feel betrayed by you, as well as by their father. I would not want to risk that.

As with all the other posters I think his deception is a major, MAJOR, mistake. The two children are hardly children and probably consider themselves as almost adults - I know I did by the time I was 13 and one of yours is almost marriageable age themself!

I also agree that you should refuse to attend unless he tells the children AND invites them to the wedding after telling them that they will be the most important guests. Fine if they don't want to go, but it then leaves your free to attend yourself if you wish - without sneaking there unbeknowns to them. Doing so might even show them that you approve of him seeking new happiness as everyone is entitled to in life.

It all seems to be happening too quickly for the good of the children, but they must definitely be told. They deserve that at least.

If he goes ahead without telling them he is deceiving them. That sort of thing is very much despised by young teenagers, and it won't bode well for their opinion of him when they find out.

Anyway, it sounds from what you say that the children have coped pretty well with it all so far, so it seems they are more mature than he is giving them credit for.

Believe me, the future will not be rosy if he insists on keeping them in the dark.

I also agree that he needs to realise that if he does not get a new will, his new wife will inherit all his assets on death and thereafter they will have no entitlement to anything from her when she dies.

I would do my utmost to persuade my son to either tell his children or to put of the wedding until he feels he can tell them. There must be an underlying reason why he doesn't want to tell them and it won't be a good one.

I wonder why he's told you, why tell anyone - maybe he's expecting you to fill in the gaps and pick up the pieces when the news breaks. He's obviously not expecting anyone to like the idea but hey once it's done it's done. Getting 50/50 shared care and then seemingly caring so little about how the teen children will respond is care-less. Sounds like a very manipulative immature person on the face of it but we've only heard about a snapshot of their lives. No doubt if the sh*t hits the fan you'll end up doing his 50% of the shared care & him & new wife will be free of any commitments because he'll have alienated all his existing family. That's worst case scenario.

Retroladywriting

I wonder how the prospective new wife feels about their marriage being kept secret from his children ...

I wonder if it's her idea?

You said that he knows his children will be devastated, yet he is still going ahead. That speaks volumes.

So Meow, have you decided what to do?

Oh dear. I am so sorry for this awful situation you find yourself in. Thrust right into the middle of the very likely fallout between your DS and DGC. Always, always children come should first and your son needs to recognise they will be very hurt to be downgraded to 2nd place. Not to say also disappointed, confused, belittled, and rejected. They will feel they are not good enough to be included in one of the most important family events in their fathers life. And the new woman will be happy with this? If so she is not setting herself up to have a good relationship with her new stepchildren. They will probably blame her for their fathers deceit. Your son needs to wake up and do the right thing. I do hope he does and it all works out for everyone

Oh dear. I fear they will never forgive him.
If they were babies or toddlers I could just about understand it but at 13 and 15! Has he no insight into what he is doing? They will blame her for sure but they will blame him more and I expect they won't want to live with him any more.
Perhaps that is what the new woman wants.

My parents did the same thing to my sister and myself , we were slightly older than your sons children , my mother told us she had married my stepfather the day after their wedding and my father did not tell us he had remarried for a month, we were both very upset and never really trusted either of our parents ever again, their excuses for not telling us was they did not want to upset us!!!

Have you asked your son why the rush to get married ?
If he is sharing 50/50 custody I assume the children are living with him half the week so what does he think is going to happen in a “few weeks” when he gets married assuming the new wife will move in too ?
It’s short sighted and cruel to teenagers adjusting to a life upheaval.
As his Mum you need to have a frank conversation with him and spell out the grenade he is proposing to throw.

It’s just wrong on so many levels to do something as significant as getting engaged and planning to marry whilst lying to his children. ‘Madly in love’ is such a juvenile dramatic way of describing their affair. Does the new wife to be have children?
These children are at vulnerable ages to be dealing with the end of their parents marriage. It’s positive they’re beginning to accept the girlfriend but that’s very different than expecting them to welcome her as a step mother.
OP in your shoes I’d be honest about how you feel. If they insist on this haste marriage, I don’t see how you can attend without colluding in the lies to two children who need stability and decency from their parents. He may find he isn’t sharing 5o-50 care of them if they de-camp to mums

I am a straight talker with my son and would tell him that I think he is being selfish and cruel.I would advise him to not only discuss this with them but actively encourage them to be involved. I would definitely not attend the wedding or want to have any part of it. His children deserve better treatment than this they have feelings too and will probably never get over such deceit. He is not a lovesick teenager he is a grown man and needs to act accordingly.