Becoming a bitch by experiences is fine, it keeps your defenses up. I hope you also learned to recognize those for which you can lower your defenses. The thing is, several people I know that are bullied in their childhood, have become the most gentle and amiable people. They apparently learned that you don't have to fight to be happy. The bullies on the other hand (I mean the real ones) often never stop bullying, scaring of people their whole lives. They may feel powerful, but often are lonely and pitiful.
If your gonna do something, give it your all and do it right! ?