First off -- I want to take issue with your comment "Years later I now see that due to the unfortunate situation he was in, he had no choice but to exploit my feelings to get what he needed and seeing my lack of boundaries he continues to do so." I disagree with that statement -- of course he has a choice, no one is forcing him to exploit your feelings." Some people would sense your vulnerability and want to protect you -- this guy does not. With that aside, I think that the sentiment behind what the other member posted, regarding daily affirmations and some yoga gets to the heart of what your struggling with -- how little you value yourself. You have pointed out that you have been abused and neglected, and no doubt that your evaluation of your self-worth stems from those experiences. And I think that the place to start from is why you don't feel that you deserve better, and to begin to develop a feeling that you matter. I think if you felt that way, you would figure out what to do about this situation with this guy (which I think would be you'd find a way to leave). I realize that you may think that it seems impossible to imagine that you could feel better about yourself than you do, but with help it is possible.
Maybe not the exact same situation, but good gracious. Preaching to the choir sister (24 year old naive thing still crying about how crappy life is). I am waiting for this answer.
Daily affirmations in the mirror are slowly working for me. "Strong, beautiful, confident." That and some yoga.