Don't let him hold you hostage. Trust me, I know how that can be, although my situation was different, and I won't go into it now. He controls you out of fear, and you need to get yourself in a place where you have your independence to fight back, whether this means leaving him or not I don't know but he needs to be put in his place and stop holding you hostage. Keep looking for resources. First, find friends that will be supportive when you're home and have them over so that it can be 1. a way to keep him from being abusive (abusers tend to act "right" in front of outsiders) and 2. if he does act out, you'll not be without witnesses. I know your sons see it all but they can't be relied on if he ever pulls the crap that you're unfit as a mother. Your Mother in law needs to go. I know that's probably likely very hard to have happen now but she really is just making things worse.

You've mentioned you're starting to work again? There is NO reason he needs to see your money. he hides the finances from you? CREATE YOUR OWN. Get that job, get your own bank account, leave his name off of it, and start building your own finances. I would say keep the existence of it from him but that's pretty impossible since if you're working, he'll wonder where the money is going. You're in control of where YOUR money is deposited and even as your husband he has no say in where it goes. Ideally it would be shared but clearly he's not sharing himself so no reason you should. With this separate income you can work toward getting help with a lawyer and be prepared for whatever outcome, up to having to leave the situation without the threat of him taking everything away.

You are not powerless, do not let him make you think that! You have rights, just as much as he does. Another thing is, he may not know this but if you divorce and he's pretty much held you hostage and kept you prisoner financially, he'll end up paying you. But you'll need a lawyer.