Bf's friend told me he cheated on me

The friend thought it was funny to joke around and tell me my bf cheated on me and brought another girl over to the house. Little back story my bf rents a room at his friends house who is the owner of his favorite bar. I was sitting minding my own business eating my food at the bar when he approached me to tell me "you got real fat Letty" I actually have lost Wright. Didn't know what he was talking about. Then he came again and said "you're acting different. You don't remember when you came to the house with Philip to eat with us with?" My bf just moved to the apartment while I was on vacation so I have yet to go and my name is Elizabeth. Absolutely no way you confuse the two. My bf and I have been rocky lately so I ended up crying that he cheated on me. Instead of getting mad at his friend he got mad at me for believing it. He said "you know he fucks around with you a lot. Dont let him get to you."

The friend ended up coming back to the table to clear up he has never brought a girl over and was just joking with me. I have only met this guy once. He and I are not close for him to be joking around with me with a topic like that.

He ended up taking a photo that night off-guard of us two arguing and sent it to him. I told my bf that's pretty fucking creepy to cause us to fight for entertainment and then take photos of us arguing.

But my boyfriend thinks I am the problem not his friend. Am I the one who finds this crazy and ridiculous he would be on his friends side?