"I hate myself for turning my back on him." Yes, and he is counting on that!
You are not turning your back on him. You are stepping back and giving him the room to grow. You are letting him feel the consequences of his actions. You are taking care of yourself instead of enabling him. He will do his best to make you feel like sh*t for that, but IMO you are doing the right thing. If you keep enabling him, you will just have to go through the same scenario again later on down the road.
Search your heart. Know in your deepest self that you are not doing this to hurt him. You, of all people, know that recovery comes from within, not from relatives.
((Hugs))
Babs