Hey PT, the fact that he's actually told someone about the abuse is progress, and I'm sure it wouldn't have happened unless you leaving caused him to take a hard look at himself and his addiction.
That said, admitting to past trauma is just the beginning of the journey for him. He knows there are many resources out there to help him, but he may have counted on you flying in to rescue him. You've done the right thing by standing back. He will either step up to help himself, or shove it back under the carpet.
Imagine if he finally organises treatment for himself. It will have so much more value that if its arranged by you.