The Mole

I don't know if any of you have ever watched a spy movie, but in these films there is usually a mole, as I know from my James Bond (or, more precisely, my Pierce Brosnan) obsession.
This mole tells the secrets of one party to another party. It's a total betrayal.
In girl culture, it's part of Girl Code that we avoid being Moles. In theory. In practise, there are many Moles (who are also called Gossips or, in an extreme sense, Bitches) amongst us.
In boy culture, I think they're all Moles to be honest. If you tell a guy something then you are also telling his 10 closest friends.

I'm in a slight confusion, because today I finally mustered up the courage to talk to my friend (the one who kissed Curly Haired Guy, the boy who I currently sort-of like and he likes me too). She was slightly cold (which is fair enough given the circumstances!) but she also added that she knew that I kissed CHG [Curly Haired Guy] at a party we went to the other day.

HOW DOES SHE KNOW THIS. The only people that knew were:
1. My close friend who doesn't really talk to the other Friend
2. One of my other friends who told me to keep me and CHG under wraps and not say anything - hence why would she tell the Friend?
3. CHG, who I told not to tell anyone about our kiss or it would cause problems. He promised not to.

So who's the mole?
I'll leave this one up to you, Pierce Brosnan.
I'm confuddled.