Bf can’t understand he accused me !!!

Ok so my bf accused me of having sex with his friend, this friend accused me of having sex with him for years . Flash back , this friend I knew in high-school along with my bf , way before me and my bf started dating like years , we in high-school his friend wanted to talk to me never found him attractive.. ok so flash forward after me and my bf started dating he tells my bf whenever he feels like it that we did something, if that’s the case why would I lie if it happened before we dated .. I lost my v card to my bf but when my bf gets mad he says I did cheat on him with his friend and we had sex , he just now recently says him and his friend was bout to fight because he once again said we did something, my bf let this man feel comfortable saying that to him . We went to his friends house & he immediately tried to talk to me my bf was like “Na she’s with me “ like a month later this man that I don’t know said he seen me out at the club I don’t go clubbing , his other friend said I was beautiful, obviously his friends find me attractive & this one friend that this whole story is about is the one that goes the hardest . Ok so like yesterday my bf and I got into an argument and he says I cheated on him & it hit close to home , he was trynna say I cheated with his friend , so like 2 months ago when my bf got mad and accused me I tried to hit his friend up ,& let him know , I ended up sending “rhhcgh” his friend responded with a “?” I blocked him , my bf accused me again so I unblocked him , now our argument is “he accused you of fucking him it’s disrespectful for him to be in yo imbox” (on fb I don’t have his number ) so I said as long as you accuse me & him of fucking he’s going to stay in my imbox , he says that’s disrespectful but I feel like I make good sense how do you want him out my imbox but you get to freely accuse us of cheating with no proof !! I feel like his friend is obsessed with me & what man is going to allow another man to lie on his girl with no proof , my bf said how do I get mad at him (my bf) but not at his friend like why does he feel so comfortable to say what he says about me that’s a man and that’s yo friend , you should handle that not me ! .... oooh let me add this I got locked out my old fb , I did try to check his friend on my old fb in front of my bf , I inboxed him and asked “why are you saying we have sex “ & he responded “idk did we” like I said my bf was rite there so it’s no secret I’m tired of dealing with it obviously his goal is to break us up & my bf is letting him I can’t deal with this for the rest of my life