Eden, having done some bad things doesnt mean you are a bad person. You regret them and that is a sign you have a morality. Feelings of guilt belongs to depression and thinking bad about youself too. I have the same, i regret some things and feel very guilty about it. But i try to think its the depression that makes us feel overly guilty. We cant change the past but we can act in a different way from now on. That might not take the feelings of guilt away but at least you did and are doing things that are good, make you a good person. Dont identify yourself with actions in the past. Whatever those actions are.
Try to find some distraction from those negative thoughts.
Take care.