Hi Anxious,
Firstly, he's out of control and dragging you and the children down with him. Whether he's capable of seeing that is beside the point. You are the responsible adult and need to either get him out of the house, or leave yourself. He will of course bombard you with love, promises, pleading, tears. Be ready for that, because you're going to have to stand firm.
You're at the end of your tether right now. If you feel you can't leave right on Christmas, get through that, then plan to separate afterwards. You should be able to Google domestic violence services and give them a call at least. You don't need to be subject to physical violence to qualify; he's depriving you of money for the family as well as gaslighting you (pretending about the purse is an example). The people on these help lines are very experienced in helping out during a crisis and putting you in touch with the support you need.
It seems you have some support from family as well. You may need to tap that resource as well, if you think it will help. Does your work provide DV leave? I'm sure you would qualify.
After you've spoken to the DV people, I would say your first priority is to secure your finances so he can't get at them. Whether it's a stash of cash left with a friend, or a secret bank account where he can't get at the PIN, find a way to secure your money.
There's so much going on it's hard to know where to start, but I would ask you to please look at getting yourself and the children away, then tackling what needs to be done in small steps. Best of luck, and stay in touch.