Do you know what i can say?

ok so my boyfriend and I been dating for 4 months. We started fighting about three weeks ago. but always made up. But a couple days ago one of my close friend kissed me. I told him. but lately he thinks im cheating on him with that guy because i still talk to him. But at the same time he has a best friend which is a girl. She doesn't like me at all and she told me this last night after i asked you she doesn't like me and if we could be friends. "all you need to know is sooner or later you wont be having a boy.bcuz you dont know how to treat him rite. i bet i can do a better job then you!! i wont f*** up your relationship but your the one who going to f*** it up" So today my boyfriend came over so we could talk and figure out what going on between us. but his phone kept going out it was her and other girls (like his ex's) there alot of girls who want him. but i think he cheated on me with his best friend. she been living with him. she sleeps in the same bed and when he asleep she texts me ugly things. But there things i havent been completely truthful about but i told him everything. So a few hours ago he send me this texts"i going to let you go so you can think about what you have to said lie too me or tell me everything you have to said dont f*** up now bcuz diz will be your second change and your last one so when i wake up tomorrow i hope to read something honestly and trueful bye!" my friends say i should just break up with him bc their no way we really going to get ago anymore. But my heart wont let me. i dont like breaking up i like to be able to work things out. any help?