My 14 year old bestfriend is so stupid,she is doing sexual stuff and she won't learn from mistake?

well, about 5 months ago she got with a boy whos 16, she "loved him" aparntly :| i've never liked him, i knew all he wanted was sex, she is so stupid so they both jumped in to do sexual stuff the second time they met, ANAL UNPROTECTED! dont worry i found it absaloutly discusting aswell, i was nearly sick, she said she didnt want to so i said ok just dont let him do it again, i hated him even more at this point then she decided to do anal 4 more times, shes been fingerd and everything, and she cant say she didnt want to do it, because she did some stuff to him, EW. anyway i did get in a big mood with this but last week they broke up, he said it was because her mum didn't like her, i was so happy and then he changed his relationship status on facebook to in a relation ship with another girl, so he basiclly blamed my friends mum... anyway my friend messaged this girl he was going out with saying, dont trust him he will treat you like dirt, she said okay, i was going to finish him anyway, he blocked my friend from facebook and then rit a status about her saying " i never loved you i used you for sex and i cheated on you" and alot more.... I HATE HIM, anyway she said she was going to forget about him, and i found out today she is going out with him again! i fell out with her, but then i was like, what is the point of falling out with her there is no point! i wont care next time if she comes crying to me saying "he cheated on me again" or something i would just say well tbh i dont care, you knew this would happen, she is thick! but i do care, she is my bestfriend we are only both 14 and he is sixteen, and he is obsessed with sex! thats all he wants, but she thinks shes in love with him .. listen to this...he got in a mood with her cos he couldnt finger her cos she was on her period, how dirty is that, i have warned her time and time again, but i dont want something bad to happen, like i mean really bad... SOMEONE HELP!