need advice

i don’t even know how to explain who this is about. we dated for almost a year and our relationship was great at first and then i slowly started going downhill. we disagreed on too many things and he told me that there was another girl he had feelings for. this was about 5.5 months into our relationship. i was crushed but i love him so i forgave him and he told me he wouldn’t speak to her again. he didn’t. i broke up with him in the beginning of the summer but we never really stopped talking. i’m still in love with him and he’s still in love with me. we got back together but my parents and friends hate him. i just found out he started talking to the other girl again and he assures me that he just wants her as a friend. i know that he’s lying and that he still has feelings but i can’t stop loving him. i don’t want to let him go, i feel like i made a mistake in breaking up with him because i have never regretted anything more. what do i do? i just want to be happy with him again. please help, this is killing me.