Hi Audrey, I think you know you're not a bad person. You're scared to let yourself hope because you love him and he's let you down in the past. If you allow yourself to hope the let-down will be even more devastating.
I hope putting the post out there has helped you clarify your thoughts. There's probably no easy answer except time. Can you talk to your BF? Or if he can't handle it yet, a counsellor or Alanon. All the best, I hope you hang in there and your BF stays sober. There are plenty of happy stories on this website.