Its amazing how many Halachic opinions there are here without quoting any sources.
It does say I think in Simin 82 Even Hezer that in case of divorce the mother gets full custody of the children and the father must pay child support to the mother. It also says I think in Simin 115 (or around there)that Beis Din will force a man both physically or monetarily to give a Get it the right circumstances (as they see fit for example if he refuses to be with her, beat her…).
As for who is at fault I don’t think it makes a difference, anyone who thinks it is ok to keep someone in chains has something wrong with their head (it also says in the Torah that if a person is a Mumar we should try to kill him (Simin 412 Choshen Mishpat) not everything in the Torah has to be done rather we listen to Chazal.
The best solution is what works today. 1. Beat him up (you might get caught and thrown in jail, but this has the best chance). 2. Through ORA you can protest at his house. 3. Get him to Israel and thrown in jail. 4. Get his friends and neighbors to help out.
My heart goes out to anybody in a situation like this. A true ????.