Why does it take so long to recover from a break up?

My ex and I have broken up, gotten back together, broken up and gotten back together several times over these last two years. He wants me to be someone else and I am not prepared to change. It is mostly about money and frankly, I work very hard but I also have many other responsibilities. I work full time afternoons and evenings but I do a job that I love – whereas he does a job that he hates, but blames me for his choices. We are both self employed. I am a teacher and he owns a property services company. He has 5 staffers, one of whom, is my son from a previous marriage. I make about 35 bucks an hour. He makes over a hundred thousand a year. He wants me to work as hard as he does, and he believes that I am "willing to take what he produces". I feel like nothing more than part of an equation. He gives mixed messages all of the time. One minute I am great, the next I am horrid. He calls me lazy, fat, and hasn't had sex with me in five years, (and although i could stand to lose a few pounds, i am far from obese!). About four times a year he smashes things and acts like a big baby, a spoiled child in fact. I feel balanced – i work hard, have friends, keep a home, look after my son, take care of my finances albeit i do have more on my cards that I would like! Over all, I am pretty good in my skin. I deserve better, but won't deny that for ten years I have loved him. I still miss the man that I dreamed about, but he will never make life easy for me. He came into the house while I was out and brought me a huge bouquet of flowers for Valentine's, and a nice but simple card. When I asked him why, he said, "they are just flowers, and I thought you might feel lonely on Valentine's." None of my friends think I should consider returning to this somewhat abusive relationship. But God it hurts. I can't understand why he has any kind of emotional hold on me. Any thoughts?