Often the answer lies in our back story as to why we tend to pick the wrong person in relationships. That is what a therapist can help you come to realize so you don't keep ending up with the wrong person. I just think from what you share that you must have incredibly low self esteem to give a person like this man so much control over you. The strength to leave comes from building your self esteem and you can't do that when you accept or give others control over that. What you have shared is so unhealthy for you, my heart aches for you.