Yeah -- I've been that 'fun' party alcoholic. I assure you, it's NOT all fun.
To be honest, it sounds like you're well out of that relationship, as he'd obviously rather align himself with people who will enable his drinking than try to stop.
You are no longer with him, but a lot of the pain you are suffering is the same as if you still were. It may be worth going to some Al Anon meetings. They could help with a lot of those feelings so that you can recover from this experience so that you can move on from it and become ready for a new life, and new people, and maybe a new, emotional healthy, loving, respectful and responsible partner one day.
Please try to understand that his sickness, and the decisions he makes to enable it to progress, are in no way reflections on you.