I started to write a textbook psychology version about ego, and decided not to go there. Quite truthfully, I think it is compounded by early childhood negative messages and fear. I also think that many that are abused display classic symptoms of depression. And when one has played some version of negativity for a long time, then we seek out people that validate these things.
The only thing that can cure the serial abused is awareness. But in a way, I don't think it will ever leave. We can only be aware, like an alcoholic is aware that drinking is bad.
I stopped allowing men to abuse me. I stopped letting my Mother In Law abuse me. Instead, I allowed my bosses on my job to abuse me. So basically I traded my insecurities from one form of abuse to another. Now that I'm aware of my job abuse, what now? Maybe some day no one will be allowed to try to make me think less of myself. I ought to be quite a crazy old woman in the nursing home. Those health care workers better be nice.