I can relate.
I grew up with an violent, abusive, drunk father. He used to beat my mother up when he was drunk and we spent most of our childhood trying to tiptoe around him trying not to upset him. I am one of three children and my two brothers have nothing to do with him, I am the only one who is in contact with him now.
Unlike you, my parents are no longer married and I suppose because he is my father, that is the only reason I still bother with him.
But to this day, he takes no responsibility for his past behaviour and I realise that I can't pretend any longer with him.
Like you, I am so angry and I don't really understand why now, why the anger hasn't materialised sooner. In fact it isn't even anger it's pure rage and hate towards him.
I feel real guilt about it but I have decided to stop all contact with him now, I am walking away for good this time.
I wrote down my feelings in a letter to him but I didn't send it, then I ripped it into as many pieces as I could. It helped, that and talking about it to people who do care about me.
You need to let the anger out, otherwise it just eats away at you.
I feel for you, I really do. It will not be so easy for you to walk away because of your family.