Dumb girl thinks shes better?

Theres a real dumb girl in my class who thinks she has a better chance with every guy in the class. well whoever she likes they never like back, because shes a drama mama, and crys over retarted things and throws a fit over chairs. shes also overweight and gets made fun constantly. shes just rude and spreads rumors around that u like so and so and Ive told her to shut up many times and stop talking about me but she tells my bff to run away from me and stop becoming friends with me. when i confront my bff she says she was just having fun. i told them both to stop and she says im not doing anything.she also told everyone who i liked, luckily noone believed her. she also told my crush, luckily he was damn fine with it. im sick and tired of her, and im trying to avoid her, but plz just help...