Omg what have i done! :|?

do exactly what you said. or tell her. just say that you made a big mistake, and idkk, just explain that it will never happen again. were you drunk ? if so, use that as an excuse and say that you would never even WANT to date him, and that your friendship means way more than one guy. she'll understand. and if she doesnt, well, its her loss cause you seem like a goodfriend, even if you didnt make the smartest choice. **** happens. :P