WOW. You have a very complex situation that probably has to be dealt with in sections rather than as a whole. Keep in mind that you will have to work very hard to prove any of this, and it will be very expensive.
Here’s where you shot yourself in the foot. First, HE didn’t accumulate the debt, you BOTH did since you were married. You could have requested a credit report and seen what he was doing. Second, you should have called the police and had him arrested for aggravated assault with a weapon. He would have gone to jail for five years. Third, if he was truly as outrageous and violent as you say (and I honestly believe you) then you could have looked into having him involuntarily committed.
Finally, he has all the things you agreed to give him. And that’s it. You might be able to prove to a court that you were under duress which could make a contract null and void, but again, you’d have to prove your case. If he has an arrest record, that helps; if you could videotape his behavior, that might help…
But remember that all of this takes MONEY. If you truly believe that he is nuts and a threat to your child, consider terminating his parental rights. He’d probably concur. If you’re scared, record the conversation, and use the evidence to ask a district magistrate for a restraining order.