My backstabbing friend ruined my relationship?

this guy and i weren't going out but we were almost there as soon as we started having some problems of where we are going to go we got into fights of betrayals and etc. (long story don't ask). i later realized this girl who was my best friend was telling him things and turning him against me. Now things are so bad me and him don't even talk anymore to a point where he hates me i don't know what to do because he even warned me about it. i am in love with him. he was my best friend and now i don't know what to do to get him back. He won't even listen to what i have to say. because she said so many things to him that he believes her over me! Can you help me?