AIBU to think my husband's ex needs to accept the divorce and move on ?

It’s a bit patronising of you and odd that you’re giving it so much thought what she should be doing with her life. She didn’t want to split up with him and she’s probably got more sense than to bring another random man into her house with her kids. I know it’s a rare concept these days but some women are still decent and put their kids first.
If you can’t understand how she feels he might show you one day. He’s managed to up and leave one family for whatever reason, he could do it again.

Yes, this is why the OP is coming across as immature and self obsessed - she seems unable to understand why the ex wife might be upset and unable to think that it might be for other reasons than the ex wife "not having moved on" from her ex husband.

Plenty of posters who have been in the ex wife's position have given their views as to why the ex wife would feel like this is a blow to her, mainly centred around the three children she shares with the OP's husband, but the OP isn't taking any of these views on board and seems desperate for people to slate the ex wife and to create a false narrative that she is stopping the husband from moving on.
Which clearly isn't true as he has quite happily moved on into marriage and fatherhood for the second time.

I’d worry less about your step children’s mother and more about how you are going to cope with a baby with a 50 year old father.

Whatever happened to support om MN? Most of the posts are the opposite and judgemental. Your DPs ex was initially hurt and responded accordingly but this could change.You seem happy in your world apart from this. DP is aware of this thread (but hasn't commented through yourself so maybe should?). What's the problem? Enjoy the highs and lows of pregnancy and have a good life. Get the fuck off this post and chill..

I think OP wants a) exoneration from us all because she feels a bit awkward about it; or b) reassurance that the ex is in fact desperately envious of her breeding with the man who failed her and treated her pretty badly; or c) both.

But I agree: there's nothing to see here.

The ex would have preferred her children's father didn't go on to have other children, and he has. That has disappointed and upset her. She isn't going to be caring whether he is happy, or his new partner is happy. She's going to be caring about how this impacts her own children - and I can't really see many arguments as to why she would think it's a huge gain for them.

I don't personally think it has anything to do with pining for her ex or feeling replaced.

And I don’t think having children means you’re somehow no longer allowed to remarry or have another child.

Of course it doesn't mean you "aren't allowed to." Otherwise people couldn't do it.

But some people do feel hesitant about the whole concept - increasingly so, I think, as the generations of children for whom this was a much more common occurrence are growing up and having children of their own. Many of them wish they had had as a child a nuclear family that stayed intact, and many were confronted by blending situations that didn't work for them. That isn't to say it didn't work for their parents; quite possibly it did. But that generation (broadly speaking, my parents generation) had grown up without experiencing this and perhaps saw less of the downsides. I think there is a growing shift in perception - which doesn't mean it "isn't allowed," but does mean the ex may very well have reservations or may well have hoped her children wouldn't be in that position. I think it's a bit naive to say "lots of people do it, it's allowed, so why isn't she thrilled to bits for me?"

Perhaps it reminded her of when they had their babies. It must have been a blow for him to have left after she had three! Most people would not be impressed. It must also have meant she could not then see her own children every day because half of the time they were at yours. I think that must be very hard on a parent when they didn't even choose to split.

Why are you so bothered by this and over analysing? She’s put out, understandably so - but what’s it to do with you?

The messages she sent weren't sent to you or for you to be constantly banging on about!
Seriously I think you are desperate for drama here. You are still here going on and on about the same thing and constantly repeating that his marriage was unhappy so he was entitled to leave but no one has argued against this!
If the ex wife was making your life difficult I would get it but it seems all she has done is sent two messages to her ex husband (NOT you!) expressing her upset.

You are beginning to sound rather attention seeking and immature to be still saying the same things over and over again.

There is no real issue here. His ex is upset, it's understandable and you know it is but that's it.
Just drop it and move on. Seriously!

I feel very sorry for the ex wife.

Given that you got what you wanted and are happy with life, and this woman has not said or done anything to you, I really don’t understand the point of the post. Honestly, I think you should have more grace and just empathise her experience.

The poster who mentioned the rug being continually pulled, and the other who said it’s like a wound thay cant heal (because she’s forced to have contact via her kids) are on point. New baby at 50 with teens must have been quite a shock.

You’re expecting to be a mother, you can imagine how it would feel if this happened to you.

I’m not an ex-wife (or wife) speaking here.

For now, we’re just trying to make the best decisions we can for the family we have rather than planning our lives around his next family.

i imagine this is what’s concerning his ex wife. To her, you’re his next family - and she doesn’t want to plan her children’s lives around you.

Understandably her primary concern is the existing children/ co-parenting setup she has with him. Adding a new baby to the mix could seriously rock the boat. I’m finding it odd that you can’t understand why she’s not immediately jumping for joy.

Your husband was in an unhappy situation
and he left. Now she’s in an unhappy situation - not of her own making - and she just has to suck it up.

You can be delighted by your baby news while others have more complicated feelings about it. Also this is all new to her, give her a minute to adjust.

If DH and I separated and he had another child I’d be absolutely appalled and upset for my own children.

“I also don’t subscribe to the idea that people should remain in unhappy marriages simply to avoid the possibility of upsetting the family further down the line. If a relationship is no longer working people are allowed to leave and particularly where there is infidelity. So if there was infidelity that is up to him all that would matter in the divorce is my child being considered and having a relationship with their father. I don’t think anyone can guarantee that every relationship will last forever.”

@OneGreatFawn - so it really feels like you want people to confirm that it was fine for your husband to leave his first wife and that he did nothing wrong in doing so. You keep repeating that your husband was unhappy in the marriage. The thing is that “unhappy” is rather vague. What a lot of posters are very conscious of is that when you’re going through the years-long daily grind of parenting and working, many parents can feel unhappy in their relationship and it’s easy to assume the relationship is the problem and the grass is greener elsewhere. However, the grass is greener where you water it. Midlife crises are a thing and relationships require work. It’s entirely unclear whether your husband made any attempt to fix the relationship or whether he was quick to walk away.

But all of this is irrelevant. It’s history and it’s done now.

And you have done nothing wrong. Your husband has met and married you. You now have a baby on the way. Your husband’s ex has some feelings around that which, in truth, just aren’t your business. You can’t change them; you can’t fix them. Put them out of your mind. Enjoy your pregnancy, OP.

You sound like a lovely person and so very considerate of how his former wife feels. I love that you have close relationships with his children, you’re doing a great job as step mum. I think she’s still hurting, most of us have been hurt at some point, and I know you had no part in the breakdown of their marriage. She also knows this, and just needs to lick her wounds a little longer. You and your husband are rightly excited ( the children too) but continue to be respectful and keep her knowledge of your lives minimal. Let your hubby deal with any parent stuff between them and you immerse yourself in all things baby. She’ll be ok, I love that you care. Congrats on baby! 🥳💕

OP how will you feel if your relationship breaks down and your partner has another child; you then cannot move any contact weekends, holiday dates etc as they’re arranged through some complex triangulation around what will be three households, university terms and likely three seperate school calendars.

You might then think ‘ffs pal, I don’t care that we’re not death do us part or how many new partners you have but did you need that 5th kid, this is making my life more difficult than it needs to be’. That’s where she’s at.

I've read though a lot of your posts and a lot of the replies and I think it's boils down to one thing on Mumsnet. You as the Stepmother are being absolutely unreasonable by wanting the ex to move on, how dare you!!! And how absolutely disgusting it is that you have a great relationship with his children, what a vile person you are!!

Now please realise I'm only joking, I'm a step mum, so I totally understand where you're coming from. Women don't ever seem to want their children having a loving relationship with a stepmother, been there done that got the t shirt. If the roles were reversed in this story, and the ex husband saying the exact same thing to his ex wife, there would be hoards of women on here telling him it was none of his business and how dare he interfere in her trying to move on.

Just try not to let it bother you, easier said than done though ❤️

Why have 3 children with someone you aren't happy with in the first place? The youngest is 11, so they must have been very young when he decided to dump and leave his first wife. Yes he has the children half the time....but it isn't the same.
I dont blame this woman for feeling like this.
You also knew what you were taking on when you married him.
As a previous poster said she will feel differently when you are dealing with the awful teenage years in your 50's and 60's. Hopefully it will then be her time to be happy again.

You seem very defensive about remarriage. As other posters have suggested, nobody really cares if you go full Elizabeth Taylor on the remarriage/s- if there are no children involved.

You are not the one bringing a 4th child into your existing childrens’ lives at a time of upheaval. No-one expects you to make parenting choices for the 3 kids, but you did ask for opinions on why their mother might not be happy.