It's easy to forget in a relationship with an alcoholic that we deserve to be happy and peaceful even if it means letting the alcoholic go to find their own way.
Your guilt is misplaced. He is not a child you have abandoned, he is a grown man and responsible for the consequences of his actions. You don't have to convince him of that fact in order for it to be true.
Have you considered going no contact with him until you can move past this place where you are susceptible to his manipulation?