Boyfriend vs. bestfriend?

alright so I'm 15 have been dating this one guy for 3 1/4 years on and off and he is my neighbor. We have had sex and everything and he was my first time. I feel so connected to him and not embarrassed at all around him. About 2 weeks ago one of my other good friends told me something I wasn't expecting. Her boyfriend (who is also my neighbor) told her that my boyfriend had sex before I did because he had to kick the door down because they wouldnt come out.and he said I was his first. I was so devastated so I asked him myself and he admitted to it. The following week he broke up with me because baseball was more important which is not a good excuse at all. So i told him i was done and not to talk to me. Then he sweet talked me, said he was sorry and we've been good up until two days ago....my best friend told me hes been talking to another girl! So he claims that their "just friends" but i think its shady. Now my best friend who told me about the other girl said she wont let me go back to him because hes a jerk but i still love him and he thinks he deserves another chance to prove her wrong.I have no idea what to do. I don't wanna loose the guy i love and my best friend. please help