Rational knowledge vs emotional response

[ScalingTheCliffsOfInsanity]

Ugh. I'm annoyed with my own self. Please help me understand why I feel like this.
I split up from my xh about 3 years ago and moved back to the uk with the kids (he's English too but working in Europe for now) about 2 years ago. Totally my choice and I have not regretted it once. We were together 20 years, have an 11 and 7 year old. He was borderline financially and emotionally abusive, but if you met him he's educated, funny and charming. I do not want him back. We work hard to get on well when we see each other with the kids. He told me earlier in the year that he's got a girlfriend. That's fine too. He lives on his own in a foreign country so I'm neither surprised nor bothered about it. I've never asked anything about her as it's not my business. However she popped up on my Instagram as someone I might like to follow (not sure how other than related contacts). I didn't realise who she was until there were pictures of them. Fine. But then I started feeling annoyed. She's nearly 15 years younger than him (birthday pics with age balloons) which means she would have still been at primary school when we started dating in our early 20s. This has irrationally annoyed the hell out of me. Why? I don't want him back.
I know rationally lots of things but how do you stop the totally emotional response?
I love my life now after being unhappy for years but maybe it's because I see him in these pictures going on long weekend breaks together and looking totally carefree when I know actually he's not bothering to speak to his kids more than once a week and only sees them every 3 weeks or so. He's really very self centred/ selfish.
How can I stop feeling like this? I hate it but I can't stop it.

Sounds like you hit the nail on the head - you don't want to be with him and don't have those feelings for him anymore, but it's frustrating seeing him having all the freedom and fun you'd have had before you were married and had the children.
You resent that he has that freedom and you no longer have that choice as you have the children to consider. It sounds like you're a great mom who will always put them first, whereas because he's in another country he doesn't have those responsibilities. He'll also get to be the 'fun dad' when he does see the kids too.

Do you think you ever get past that deep down hurt? When I think about it he really fucked me emotionally for years. These days I can see how he works but I think the damage goes deep and sometimes it rears it's head

I think it'll start to fade. There are times when you'll have these strong feelings again, particularly if he was to get engaged/married/have another child.

You'll resent him/her/them but just remind yourself that you're much better off without him. You'll always be happier with the love of your children and without worrying about his emotional abuse and, as your children get older, they'll be very aware of who was there for them too.

Thank you. I think I needed to hear that from someone. Let's just hope those times it does rear it's head (like now) become fewer and further between. I think I'll feel better when the divorce is completely finalised too.
Maybe it's time to work on me?

It's definitely time to work on you - you deserve it! X