All you really have to "understand" about this disease is that you didn't CAUSE it, you can't CONTOL it, and you can't CURE it.
Alcoholics do insane, destructive things when they are in the grip of the disease. The hurt themselves and they hurt others. They do it because they are alcoholics.
Your experiences were painful, but you don't have to hold onto the pain. You can let it go. Continuing to suffer is not going to change him, and it won't change your life. Letting go of the pain can change your life.
Stick around here--we can all recover.