I certainly have done a thing or seventy that I am not proud of. I mostly hurt myself though. Some things are done out of pain or addiction or other unhealthy moments in our lives. Some things I did were for no good reason other than selfishness.
I think in order to forgive myself I had to become a different type of person, more mindful and more sensitive to others. I have done things to people they did not deserve. I have also had things done to me I didn't deserve. It is what it is and the past is the past. I have to change and move forward. If I try to do the right thing, I'm not adding to my list. The things that are in the past have to stay there. "Accept the things I cannot change."