You take the alcohol out of the alcoholic A-hole, and you are left with an A-hole. Maybe that is just the way he is.
Maybe he never got to step 4. Maybe he is a dry drunk. Maybe he is still using, like LMN said.
Whatever it is, it doesn't matter. What matters is that YOU don't take HIS resentments to heart. He can't change you any more than you can change him.
Don't feel guilty that you divorced him, it was the right decision, and he is angry about that, but that is his problem, not yours. HE needs to get over it.