All I can say is mate, a friend of mine did the same thing sort of, the rest of my friends wanted to go kick the crap outta him.. I was like, naw...
Just watch yourself, I wouldn't take it any further man.. obviously you are concerned which is a good thing, there are plenty of other girls out there man, leave your mate with his and you go get something else
As much as you might not want to, it isn't really right and with the way the world works today you'll prolly get in some serious trouble unfortunantly.