I'm mostly disturbed by the general lack of morals in your friends yo. That whole situation is just so wrong on so many levels and I would not trust either of them to be a good friend, since they obviously can't be good to the people they are with. I don't know, deception just isn't a good personality trait, and also the bat to the head solution seems to be the best one, other than just walking away.
I would SO be telling dudes girl.