You're addicted to the drug known as "bad boyfriend." The only way you'll get over any addiction is with rehab (your therapy) and by going cold turkey (no further contact whatsoever). You didn't answer whether or not you have spoken to your therapist about your abusive relationship and your codependency? What does he/she tell you about keeping in contact with your drug of choice?
Have you ever read Codependent No More? If you haven't, you should. I think it will help you to see yourself so that you can overcome what ails you.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion