The biggest step you can make is acknowledging that you did some damaging things in your past and that you regret it. There are lots of people who never (or don't want to) get to that point. You're ahead of the game.

I'm in the same boat as you (ie. doing wrong things in the past). And I don't like who I am due to mood swings, etc. and I'm ostracized wherever I go. Part of me has accepted it and vice versa.