Why am i with him????

I have bee with my bf now for 10 months nealry 11! And we have said we are splitting up a few time and we never do. its like if one ov us says we shouldnt b tugether we will argu n thn start talking normally agin its like we both no its nt the end. He speaks to me like im a stranger, calls me names tells me he dont want me or need me and says i deserve to be spoken to like that cuz im lazy and not lookinf for a job. but i hav started looking for a job and he has been so distant. never txting me never calls. it just generally seems like he does not care about me. i found out his been speaking to this girl iv asked him not tu cuz she likes him n works next door. ok she works next door but she txts him n asks to meet him outside for a fag n stuff but he gt he number when we wasnt tugether! he leaves work erli n lies about it. n i no cuz mi mate works the sme place he does. he gives me one worded answers, he never talks things through with me just wants to argu about it neer listens to anyting i say. But the thing is when ever i say i dnt wana b with him he either says ok n then i want him bak or he asks me not to leave n i stay. but lately he just says ok i dnt care. why wont he finish it if he dont care? why do i feel i have to have him in my life? sorry its long xx