I'm stuck im best friend has an eating disorder, she makes herself throw up after she eats!!!! how can i help?

she has a very stresfull life she doesn't get very good grades! her Bf always break up w/ her cuz she wnt put out i hate seeing her like this it's KILLING ME!! i told her my life has been wors than ures u wer't RAPED. but if u don't STOP i'm gonna start doing that **** 2 i deffinitly have guy problems also w/ mai bf idk wat 2 do for her anyone help me PLEASE!!!!!!!!!