What should i do about it?

hi , im 13 going on 14. meaning im in 3rd year in high school . my friend was friends with another guy in first year and then they sort of fell out. now they've been friends again for a couple of months. thing is their friendship has always been stronger than mine with my friend as i dont have much in common with her and she has the same sense of humour as this guy. the guys got another friend and all the jokes the three of them make are really crude and the jokes always about me or my mum or something nasty. i dont have any other close friends and they said they will ditch me on monday as they did the other day at lunch and i sat myself the whole 45 mins. she defo doesnt fancy this guy as hes g*y so . Thanks for reading