I personally have caught a g/friend of mine cheating online. She came to move in with me from out of Province, too, about 800miles away.
She did the major mistake, and left her chat-room or msn open, and went to bed.
I came home from night-shift, seen her dialogs on the net, and that did it to me.
Either she woke up, or I woke her up, being disapointed or peed off as I was.
Told her, that I'm too angry to discuss the matter right now, but will sleep over it.
Well, when I woke up, my opinion did not change, and actually instead of driving her home (800 miles away), I put her on a greyhound bus !
Finito !