You should really end the friendship. i mean, would a true friend laugh at you when you’re not joking, and talk about you behind your back? i had a problem like that, but the girl is still friends with one of my best friends, because although she makes fun of most people, she doesn’t make fun of that girl. Remember, if your ‘friend’ is saying stuff about people behind their backs, that she would not say to their face, then they should not be saying it at all.