Why would my man do this??

He was always cruel and abusive in the past-we have been together 6 years- i cheated on him before as he treated me so awful.Now i have been the dutiful girlfriend for years.Paying for him, cooking, cleaning wiping his ***! I model, and don't have to put up with his crap, he is constantly flirting with women, or telling me i am fat.when i am UK size 4!! Anyway, now he has me grounded he has started to go out with his workmates.He hasn't been long in new job! This Has happened twice now-two friday nights in a month.His phone will be on and he will not answer it to next day, that is what gets me mad.He has a gay mate who calls him constantly-i use to talk with him.now when i am with my guy he won't answer his mate?? he won't talk to him in front of me!. He is playing up big time, just when he knows i am suffering depression, and when i am being nicest and attentive i can be to him.Why does he do this?? why does he not just leave me? and does he want me to think he is cheating.help