He says he has changed this time. Should I believe him?

I am 23, stay at home military wife and have a two year old. My husband just left for kuwait. He has cheated on me 3 times and the last time it was in my bed. He has lied constantly and I don't think I can think of any good things about him. But something inside me keeps saying stay why the other side is saying What if he really has changed? Ill never know if I don't stay. he cheated and every time he has blamed it on me, that i was being a ***** bla bla bla. He has put his hands on me numerous times, but I have also, trying to defend myself. When I was in labor with our son I was having bad contractions and he told me to shut up that I was doing it on purpose and I was keeping him awake. I have gained some weight due to the baby and all of the stress and depression. He told me last mothers day that I was fat and If I don't lose weight I don't love him. But yet now he says he loves me regardless its so confusing. Ive tried to leave but I always come back. I really want to leave but at the same time I don't and I don't know why I don't want to leave? Ive given up allot my career to stay home with our son so that we wouldn't have to pay child care. That's what he wanted. Now if I leave I will have to start from scratch and he has made me feel like if im not skinny that no one will want me. Im not fat im just chubby. I have so much emotional distress I feel so old but yet Im so young. He tells me now that He is so sorry for not loving me the way that he should have in the first place and that when he gets back he promises to do so. But ive heard the promises before and I don't believe him. I know Im going in circles I just really need some guidance. Please help me.