Controlling relationship. but i can't keep away. please help...?

Ive become aware of just how often my partner picks on me and tells me im wrong. yesterday i was distraught over some bad news, i wasnt very talkative and was to upset to try and get my brain in gear when he asked me something. he went quiet. and then said i was not answering simple questions and this is what he has had to deal with for 4 years. he swung the whole thing round to be about what i was doing wrong. i was upset and not able to really talk. he could see that clearly. he then moaned at me for the rest of the night telling me all i do wrong. that he cant deal with me etc! i really needed him to just be there. but instead made me feel worse. this happens alot. im finding that i listen to him, i sit and take all those bad words. if i shout back he ends it and then i beg him to take me back! he thinks i cheat- i never have ever. i feel i cant let go. he has ended it again and im fighting myself. its a pattern. why cant i let go? whats up with me. im constantly trying to prove to him that im good person