My friend is 13 and she is becoming a huge slut and i want to help her but how?

okay so i have a friend name domenica and we have been friend since 4th grade now we are going into 8th grade.but lately she have been acting all crazy .she has already lost her virginity to some guy that she only dated for 3 months.after they broke up, she has been having sex with soooo many guys, like 14 guys.she told me once she done 3 guys in one day! then all of a sudden she turned bi and became an athiest. not that have a problem with it, it's just that it was so sudden :P she has also ran away from her home twice. i dont think she has any home problem cause i have met her mother and father and they seem so nice.she also been dressing a bit trashy like wearing mini skirts wearing those tops that can see ur belly and all of that .she told me that she is going to be a high-school dropout :/ i have tried once to help her but she said "it's my life and i can do whatever" i really want to help her but i feel like there is no way :P i also feel like she is doing all of this for attention and for fun.and i bet that all this attention is going to slap her in her face when goes to highschool :/