Hmm. Sounds like you got walked ALL over ; but it also sounds like you let her. You teach people how to treat you and I'm guessing you never once said "no" to any of her requests, so I'm kind of pointing the finger at you - learn from your mistakes!
You've defended her a lot throughout this thread - so I'll assume you're obviously not over her and still haven't learned many valuable lessons. I think you should read over this entire thread - as I have (and many others, probably) and you might see what some of us are saying.
It is hard to let go of people when they leave and it is hard to admit the mistakes we made, it's easy to play the victim a lot of the time. Yes, you were in someways - the victim, because she knew what you were like and she knew what she could get out of you. But you were also partly to blame, you allowed her to do what she did, time after time apparently.
I don't know what kind of advice you're asking for? Sorry. I guess just move on, get away from her and understand what went wrong, where you went wrong. Start doing things for you and for no one else, you can't depend on other people.
About your childhood - yes, things effect us for a long time and maybe they always will, but I don't see how your childhood comes into this story? Are you trying to say that because of your childhood you let her treat you poorly? I'm not trying to be rude, I just don't understand that's all.
I seriously hope that counselling goes okay for you and that you can just let go of her, you'll be better off without her and if you learn from this.
To love is to suffer. To avoid suffering, one must not love; but then one suffers from not loving. Therefore, to love is to suffer, not to love is to suffer, to suffer is to suffer. To be happy is to love; to be happy then is to suffer, but suffering makes one unhappy; therefore to be unhappy one must love or love to suffer or suffer from too much happiness. I hope you're getting this down.