Replying to gone to far

okay, one of my best friends is a complete whore. and i think she has pushed our friendship too far. im now known as nics friend. last nite she was walking home and was completly sober and went up to a guy who was like 20 something (shes 15)and was talking to him for like 10 minutes before she asked him if he had a condem. so they fucked? i guess that doesnt mean much. but that was the third guy that nite. now i love her to death and is the only one who understands my skiing (everyone in my neighbourhood is a snowboarder, and im serious about that) but i still hate being compared to the slut. sometime something is goina happen and i feel tempted to send her mom a note, telling her what shes been up to. but i think that would be a little mean. any help here would help?
--stop complaining and smile --