I am pretty sure the guy I am sleeping with (casually on and off for years now) has a girlfriend. It even looks like they are serious and have been... Show More
Most Helpful Opinion
Tell his girlfriend. He's been cheating on her for who knows how long. She has the right to know and you know what? He won't tell her because he doesn't want to get caught. Tell her you never knew and as soon as you found out about her, you said you couldn't do it any longer.
I've been the girl that has been cheated on by multiple guys and I would have liked to know by her or well at least by someone before it was too late and everyone knew. So tell her and explain to her what happened. Tell her everything she wants to know, that will be the best. She can make the decision if she wants to be with the scum bag or not after that.