Wow, you are dealing with so much
Your situation is just so sad for you and your kids. He wants what he wants when he wants it, and he doesn't seem to be very concerned with anyone's feelings but his own.
I feel the same way about my dd- wanting her to understand what I didn't. And for her to never end up allowing herself to be mistreated, especially by the person who is supposed to love and care for her more than anyone.
Mine always tried to get his shots in right at the last minute so that the conversation is forced to end with him in a position of power and control. That's just manipulative and irritating beyond belief.
Do you possibly have anyone you trust who you could share some of this with IRL? A friend or family member? In retrospect, one of the biggest regrets for me was that I essentially covered for dh for years, (thinking he had a medical problem and that it would get better), so when things went really bad at one point, it was a dead end with no one who knew what was going on- no one to turn to and talk to. It's just something to think through. Only you know what's right for you, but I wish I had someone who had known what was going on all along, and who could possibly offer support. In other words, maybe don't protect him at the expense of yourself.
Hope you are doing okay.