May I ask a question? Why was he a B*****d and a loser? What did he do to you in the relationship? Was his problem just the drinking? Why did you give up on him? If he treated you badly, then yes, he was a loser, but if he had a genuine problem that needed help, could you have you had stood by him? I am only asking and I don't want to sound like I am judging because honestly, I don't know enough but it is just something I was curious about in this thread.
You also sound like you are still feeling guilty about leaving the guy but also you seem to feel guilty and ashamed that you were close to him....
It sounds like you need some time out to get over him to me. It is nobody's business but yours and you don't need to tell anyone but if you do, just be honest. Your past is your past and it does not sound like you have really done anything that wrong to me. You made a decision based on what you felt was right for you! Remember that! Still I am curious, could his problem have been resolved, did you communicate your concerns over his drinking e.t.c.?
+ What do your family have to do with it? Why do you feel guilty, did your family like him?