The people who found out said she was desperate, a slag, a cheater, a whore, etc. etc.

Well, this isn't really my story, but I was involved in it. Basically, me and 2 other girl mates and one guy mate went into town one day after school. Lets say the girl's name was Em and the guys name was Joe. Em and Joe were walking back as Joe had to catch a bus and Em had to get home, whilst me and Rowan stayed. They were messing about and being friends, even though they both were recent exes. Joe went into snog Em, and then Em - due to surprise - just let it happen. When they stopped, he went into snog her for a second time. This would've been fine if not for the fact that Joe was dating a girl called Marie. But before they could kiss/snog again, Em said, "No, this is wrong, you have a girlfriend". A day after the incident, she told me about it. I decided to tell Marie. Now here's the crap bit: even though Joe went in to snog Em, Marie and everyone else she told said it was Em's fault. So when we were back at school, the people who found out said she was desperate, a slag, a cheater (she got a boyfriend a day after the incident), a whore, etc. etc. Whilst Joe got left alone. Marie apparently said she wanted to "destroy" Em. Practically only 2 people thought it was Joe's fault apart from me and Em. 2 out of like 50 or so people. A month or 2 later, after more gossip has rolled in, most people have forgotten and Joe has got a new girl to play with.