Please help me please?

my boyfriend and i have been dating for a year and 2 months. we broke up once and then he started to change. the person i was in love with has disappapered and now im stuck with this y *** hole. excuse my language. lately we have been getting into alot of problems and i keep trying to keep this relationship together but he seems like he cares, but at the same time he acts like he dont. we talk about our problems and its lke they are in effect for that day and the next day its gone. i really wanna be with this boy but he has no respect for nobody but himself. i really need help. my friends are ellin me to be mean to him but i cant. im not a mean person. also he talks stuff about me behind my back, and when i ask him about it he denys it. and the worst part is, he tells them to my best friend and i kno she doesnt lie about stuff like that. i wanna be with him i love him. please someone help me....