should i stay friends with her?

[megann!]

my friend sally is always getting mad at completely worthless stuff, like when we have a sleepover or b/c i didnt want to go to science tutorials with her,and wanted to go to french club with my other friends lucy and sarah! [we are in 8th grade] and she is always calling me lucy's "assistant" but i think she is just jealous.

she is constantly talking behind our friend sarah's back, like "sarah is soooo dumb. shes such a whore!". She seems like she always wants to be the center of attention and is always trying to turn me, lucy, and sarah against each other!

me and lucy have tried talking to her about all this, but she just says "whatever" and gets mad. i would like to stay friends with her though, because she is my 2nd best friend!! and most of the time, we have fun hanging out.

should i stay friends with her?? or should i HOPE that if i talk to her she will change how she treats us?