To me, it sounds like emotional blackmail to say to you if you leave he's not going to be around. He's telling you he's going to do what he's going to do, and you better suck it up and deal with it or else he won't be there for his kids and it will be all your fault. I'm sorry-that's just wrong and incorrect. HE'S the one that is at fault. He chose not to go to Chicago like y'all planned. If he doesn't have anything to do with the kids, that's on HIM. 100% HIS fault. But honestly, as hard as it may be to think about, if that's how he is now, maybe they'd be better off not having him in their life. He can't promise to do things and then not do them. That's awful.
I'm irritated with him on your behalf. When you think about being on your own, don't forget you'll get child support. He can't skip out on that.