He sounds a right prick and you are well rid. I understand though that you don't feel it right now. You will soon enough!
I would spend a good amount of time seriously comparing your lives and what his life is going to be. I assume you are past the most labor-intensive child raising years. So, in the probably very near future, you will have entire weekends presumably spent alone where you can do anything you damn well please. Or absolutely nothing at all! You can spend time on hobbies that you couldn't before, and go out with friends. Or take up a hobby! If you make a mess in the house it is YOUR mess and you won't be tidying someone else's mess as well. Your days of dirty nappies and midnight wakings are done.
And his life isn't looking quite so rosy! He has all the middle of the night waking/walking around like a zombie the next day stuff still ahead of him, and it is much harder to deal with when you're older. He will look (and probably feel!) like an idiot when he's out with his baby and all the other dad's are half his age, I love the picture of strangers coming up to admire the child and calling him grandad! And there will be no weekends off for him for many many years.
You could almost have sympathy for him, except don't go that far. ;)
I once read a really trashy novel and I can't remember very much about it, the general idea was that it was a woman whose husband starts an affair with a younger version at work, and all the emotions she goes through and things she does to try and win him back. And at the end she realizes that she hasn't actually lost anything at all, she goes to the other woman's house with a suitcase full of the hubby's clothes, hands it over to the OW and OW says something like 'you mean I've won', and the woman said 'that depends on what you think you're getting'. Or something like that. I probably haven't explained very well, but the idea was that patterns repeat themselves, what he's done to you he'll do to her eventually, while you yourself are free of it now.
Be gentle and good to yourself, treat yourself and your children if you can, you all deserve it.