Op,
Imagine you were the one who ended the relationship and the children were staying with your ex. Imagine you didn’t want to be with him, but felt enormous guilt at leaving the children.
So you say whatever it takes to make it easier. “I’ll still come over a few times a week and cook tea! I’ll still clean the house for you! I’ll still come and take the children on days out! We can still go on vacation!” (I’ve chosen domestic tasks because of your clear inability to do DIY)
Now, fast forward 6 months and you’ve been going back and forth to the old house, doing your chores, seeing the kids etc when you meet a lovely guy, who you’re interested in.
This guy wants to take you out. He wants you to vacation together; but ex still wants you over there cleaning his house and making their tea.
New guy starts to feel pissed at you. You’re over there a lot and it feels like ex is taking advantage. You feel stuck between a rock and a hard place. Why did you promise all those ridiculous things?!
Now someone in the family is getting married. Everyone is invited to the wedding. Ex wants you to go in the car with him and the kids and expects your new partner to go up alone.
Op, you would not think this was reasonable behaviour. You would feel trapped by someone you had no intention of being with. His behaviour is not going to make you love him, it’s going to make you despise him. It’s needy and over involved and desperate.
Eventually you’d have to tell him no more. You’d have to, because you couldn’t live your life like this.
That point has come op, but you are the ex in your story.
The end of life as you know it... could be the start of something new, better, more independent and you are free to find love again. You need to move on.