I recently found out my best friend is having an affair behind his wife's back. This wasn't a simple one-time occurrence. It's been an ongoing relationship for months (with someone he works with and his wife has met numerous times), and it's just as much emotional as physical from what I've gathered. When I found out about it and approached him, he denied it at first but eventually admitted to it. To make a long story short, due to a large number of arguments between us, the friendship is pretty much null and void. I've known him for over 4 years, but the affair was just the icing on the cake lately and I don't need that kind of "friend" in my life. My problem is this though - I've known his wife for as long as I've known him, and she doesn't know about this affair yet. And the real kicker - she's pregnant with their first child. I care about her and don't want her to be hurt, but I'm torn as to what to do now. Do I tell her and break her heart, possibly causing problems in the pregnancy? Do I have faith that eventually he'll stop and tell her himself? Do I remove myself completely and say "it's none of my business" and live with the fact that she may never know? I'd be devastated if I found out years down the line that someone I was with not only cheated on me, but continued a full fledged affair under my nose. So what would you do?