Hi Tobrien,
I wish I had some perfect advice for you. I really, honestly believe that can get through this though. It will be a gradual process, but I'd like to think that if you can stay clean, you can make up for some of the things in your past that you feel guilty about.
I don't say that in a negative way about you personally. We can't erase what we've done in the past. But it sure does feel good to balance out the karma.
Good luck.