My friend is mad at me because i busted one of her lies?

im not sure if i should apologize or just not care haha. the story is she was talking about how she and this guy were talking and she really liked him and such so i added him on myspace. he im'd me and asked me if i knew her and if i partied with her? i told him that i didn't even know she "partied" and he said that she told him she throws parties every weekend and a bunch of people come and they get drunk? lol and that she has had with multiple guys?! all of that is a lie and well i told him that she doesn't drink, she doesn't throw parties because im with her most weekends and shes a virgin. well she found out i told him and now shes mad at me because i "got in her business" and that she lied so he would like her. the thing is im tired of her lying, she does it compulsively and its just really annoying now shes mad and expects me to apologize and feel all bad for not going along with her immature lies to make her look cool... should i apologize or just let her be mad?