Well, it sounds like your friend back stabbed you. She probably likes him herself and told you he doesn't like you in order to eliminate her competition. (you) You may not want to believe this is her motive because she's been such a loyal friend, but when it comes to guys, young girls tend to be a little heartless and deceitful to even their best friends. It happens. I wouldn't let it ruin your friendship though, because there are many fish in the sea.