How do you break up with a guy that is your best friend cousin?

we both started liking each other but when we started dating it dosen't seem right. for some reason i want to go back out with my ex boy friend. so how do i solve my problem.How do you break up with a guy that is your best friend cousin?
Its kind of funny because I too go with my best friend cousin... But I don't wanna break up with him... But I think you should just be straight up with him. Tell him things don't seem right and it would be better off for the 2 of you if you'll could be friends again. The relationship between you and your boyfriend, and the relationship between you and his cousin have nothing to do with each other. If he/she is a good friend then it shouldn't matter what happens between you and your boyfriend. BUT.. It you don't break up with him now you could possibly lose your boyfriend and your best-friend because they feel like you were trying to play with his emotions.