For starters you cant say anything. If anything, you have proved yourself to be an untrustworthy friend.
From what I can see she hasn't said anything that bad about you. I ave friends who are naive and bad judges of character, doesn't mean I don't like them. I also had to go clubbing in Birmingham to some awful garage night for my mates birthday, did I moan about it all night? No, I pretended to enjoy myself, just as she does when I force her out to indie/rock clubs with me.
SO her biggest crime is not wanting to hurt your feelings and needing to vent off.
Respect peoples privacy in future.