This is going to sound callous, but count yourself lucky. You have good memories. You are not physically or emotionally threatened. I've worked in healthcare for 10 years now, and I can tell you that from what I've observed, very few alcoholics get sober on their first try or even their second. It gets worse before it gets better.
Give yourself some time to feel your feelings and work through the loss, but then pick yourself up and move on. At the end of the day he was inherently and deeply dishonest with you on multiple occasions. You really have no idea who this man was/is.