He’s in over his head, and he needs to focus on raising his two children either with his ex-girlfriend as a couple, or as a separated co-parent with his ex-girlfriend. Someone else may be able to do this with some grace, but from what you’ve described, your ex-boyfriend doesn’t have that grace. He has his hands full. There’s not going to be a lot of room for you.
Even if he thinks things are settled enough for him now to come back to you, he’s deluding himself if he doesn’t think there are going to be big bumps in the road ahead — just as there are when any two parents split up and have children between them.
Hooray for you that you’ve found someone else. Now focus on the good man you have, and don’t get distracted from the life you’ve built after he left you, with what he wants. He had you and blew it. Game over. He showed his true colors and guess what — you deserve better. A lot better
Value yourself and you will be valued.
I hope that helps. You’ve been through a bad relationship with your ex-boyfriend. Make this new one a great one!