His having hope doesn't depend on you. He has hope whether you stick around or not.
Even assuming he recovers fully, he won't be the person you thought you knew before. Recovery changes a person completely. It's really up to you if you have the patience to wait and see what happens. No crime if you don't.
Keep going to Al-Anon and think about what changes YOU can make in YOURSELF that would make you a happier person.