Al-Anon is a great idea. However, given the history of resentment between you two, I'm not sure if you are the best person to deliver that message.
Your suggestion, which may have the best of intentions, may come off as "Hey, I know you're divorcing me because of my drinking, but the one who really needs help is YOU." It sounds too much like blameshifting. You run the risk of having him completely tune you out.
If you do say something, I would say it once then drop it. However, this is one of those cases where I'd let someone else be the messenger.