Do accept the fact that girls will tell their friends about 80% of the things that went on between you and her. Its the way girls are. Wives gossip. Girlfriends gossip. Even that girl who you're having a "thing" with gossips. Only about 5% of girls don't.
So do get over it and don't be hopping mad because she told her friend what you guys did during the weekend or how you made up or why you fought. Girls need a 2nd look at it, so they'll get a much better understanding of such situation.
As long as we're not telling about how you can't get it up, the time you dressed like a frenchmaid or how you're deathly afraid of spiders, then shut up.