To keep him away from kids’ events?

Come on, you're being completely ridiculous. Of course he spends a lot of time with his wife and kids, they're his wife and kids. Surely you shouldn't expect anything less. When you find the person you want to settle down with you usually love spending time together and want to do it. You just sound bitter and twisted tbh.

Your children sound relatively young. They probably wouldn't notice/remember how you've been treated unless you're reminding them/pointing it out. Honestly please don't do this to your poor children.

Let their dad come to the events, let your children be happy and try and encourage them to build a relationship with this woman and the children. You need to put your children's welfare before your own feelings which is what good parents do.

How would you feel in years to come if your son has a relationship that results in children and then for whatever reason he decides its not working and leaves his partner. Would you be OK with the partner stopping his relationship with kids just because their relationship ends?
You stopped loving each other. That doesn't mean he stopped loving his kids. Your attitude is going to stop you moving on. Focus on enjoying your kids you don't need to invite him or prevent him attending just move on it will be healthier for all. He doesn't actually need your permission anyway if he decides to turn up at events. You however will need his permission if you want to be petty and change your kids names...

You need to grow up - you children may not resent you now, but they will.

Everyone else isn't wrong

So what? Yeah it sucks. Grow up and get over it for the sake of your kids.

and you say he doesn’t want anything to do with your kids - he’s trying and you won’t let him.

honestly if this is what you were like when you were together I may understand why he left you…..

He could but he doesn't want to. When you meet someone will your DP be kept separate from your children? Excluded from their milestones?

Or will it be one rule for him...?

There’s no double standards.

shes his WIFE! Most women would be happy their child’s dad any stepmum wanted to be part of their life. You read more people complaining on here that the dads don’t want anything to do with their kids!

If he's a bad dad they'll figure that out without you helping it along

I understand why you're hurt. But it's not about you.

Love those children more than this

I can understand it's hard for you seeing your ex with someone new. But it's harder for your DC to not see their dad.

She isn't his GF or a new fling she's his wife. He's entitled to want his children to know her, he's entitled to want her to be good to them. His attitude to their first day at school etc might have improved due to her influence. As hard as it is for you love your kids more than you hate his wife

YWBU

Let me rewrite your opening post for you but from your Ex's point of view:
"I used to go out with a girl and we split up. I started seeing someone after we finished. We have 2 kids together (with the ex) and I want to go places with my wife including to see my kids in school plays, at their religious events or whatever. I wanted to see my son on the first day of school 2 years later but my ex said no because they knew I would share this event with my wife too.
Is my Ex being unreasonable to not tell me when there are events in my child's life because I want to share these events with my wife? I showed up once at a sports event and brought my wife too. I think my ex couldn’t cope seeing my wife and never want to see her again."

You are being massively unreasonable. He has moved on and he has a wife. This person, whether you like her or not, is stepmother to your children. You will have to get used to that.

What is going to happen when your kids start noticing that other mum's and dad's in their class show up to events for their kids and they ask "Mum, why can't Dad come to see me in the nativity/play/sports day/festival? Why don't you allow Daddy to come??" because that day will happen.

It is the case but it DOES NOT MATTER for your child's wellbeing. All that you need to put in the past. It is YOUR problem and your child should not miss contact with her dad only because when he was with you he was immature/ unreliable..... Regardless how it makes you feel, it is I portent for your child to have a relationship with her dad and for dad to attend school plays etc.

Yabu. Put your child first here and grow up. He is married and this lady is going to be important in your childrens life. You cant stop him coming to events because you don't like his wife.

You can’t stop him seeing his kids do stuff because you don’t like her. It’s life. Unfortunately, it’s not pleasant but ultimately your child(ren) shouldn’t pay the price of not seeing dad.

OP this is about you, and you need to make it about your DC.

He's being unreasonable and weird for never going anywhere regarding his kids without his wife. My dad and husband would never behave this way. Sometimes kids need one to one dad time though so he should discuss each event with them and so should you about who they would like there. As long as the kids like his wife and are comfortable with her she should be able to come to events when the kids want her there and when he does. You're unreasonable for telling him what he can and can't do around his kids. They're not objects, they're in the middle and I feel really sorry for them having to put up with this crap from three adults who are meant to love and support them. Stop it.

YABU to spoil your childrens' relationship with their father.

Does he contribute financially towards the kids? How long did you see each other for?

You need to grow up, quite honestly.

Your children’s feelings need to come before your own. You say you’re not jealous but you sound really bitter. Those children might resent you for making this difficult in future. ExH having to have wife there might be annoying but that’s the father of your children and they will no doubt want him there, wife or not. If he’s willing to show up, let him. Even if it is with his wife and you don’t want to see them. This isn’t about you.

Edited to correct typo

IT ISN’T! ABOUT! YOU!

Childish and jealous behaviour. Your ex has every right to see his son WITH his wife. Get over yourself!!!

You sound bitter and a bit mad.
Sometimes people aren’t right for each other! Use your weekends when he has the kids to get out and make yourself feel better, fuck what she thinks of you! Don’t compare yourself to her learn to like yourself!

Oh to be fair I agree he isn't being mature about it either. He could, even if OP is being unreasonable in saying no to stepmum attending, rise above that and see his children at events and do more to encourage their relationship with their stepmum such that they themselves want her to come too. He isn't making good decisions either.

If he cared at all about your kids he'd come now and again by himself. In his shoes I'd go solo and hope the dust settles quicker that way... knowing long term they will likely have a relationship with his new wife....but him not going at all would scream to me he just wants to put on a show.
If a court looked on it they might not be impressed by you but they'd definitely see him on much worse terms (theoretically).
Basically YANB2U👍