Heard from an acquaintance this weekend that he and his new girlfriend (the woman he left me for) are still together and that she's head over heels for him.
First, I would really cut all conversation about your ex with people who know him out of your life. Do not ask, they won't tell. If they start talking about it tell them to zip their lips.
Second, alcoholics are notoriously needy, will start something before the last thing has finished. It's all about them. Don't think he's changed for her or any such thing. He's the same person, particularly if he didn't have time to crash over your relationship.
One of the women in my al anon home group is very good friends with my ex, and she has heard every ounce of his side of the story and nothing of mine. She is good friends with my sponsor. It is so tempting to sit her down and tell her what he really is like. It's tempting to ask her what her perspective is. But the fact is, it's irrelevant. It's over, and we were not able to work it out.
Remember the reasons you broke up...really keep those in mind. The fact that he has moved on so quickly shows he is *exactly* the same person. Alcoholics only change when faced with crisis. Your ex has avoided that by hopping lilly pads. He's not there yet.