You are close to a person who's broken. It can be infectious if you're not careful. Seriously.
That is a very wise dude.
As far as any person can, we have a pretty good idea of how you feel. The advice you have been given is fabulous. Don't feel bad about yourself. most people wouldn't have been as gracious as you.
As for put together - you should see me when I have had to go three rounds with my crazy little bunny. Without belittling their human dignity, it can help to just think 'crazy person' when you have any interaction.
Back right off. State your terms and conditions and stick to them. He wants a relationship with his kids. Good, let him have one. As Job reminds us - we didn't break them and we can't fix them. Be a great mother to your children - as you always are. They need one sane parent.
Keep your contact with him to a minimum, and do not allow unrestricted coming and going to your home. Be pleasant and distant as you would with a work colleague, and no relationship talk. You are probably worried that this will drive him back to hww. But the reality is that whatever he does is down to him.
The thing is with MLCers they either have no idea of how other people feel, or they don't care. Either way they need to get their empathy chip fixed. If he honestly wants to be with hww and the baby that is his choice. But in that case he can't cake eat. Which he has been doing.
You are a fabulous human being and you need to stand up for that person. this guy is trying to trash you again. What a b*stard