A buddy and I play pickleball at the nearby courts where you can just drop in and play with strangers. We go to play usually on Fridays/weekends because we work pretty late so we've gotten to know the regulars who play at that time of week. Every now and then we might get out of work early on a weekday so I'll propose getting in a few games but he was never interested, which was totally understandable given that we're usually busy so I never suspected that something else was going on.

One day we finish work extremely early and I convince my pal to come out for some pickleball. When we arrive at the courts, a girl I hadn't met before approaches us and knew my buddy by name. He introduces her to me and I notice that he's acting strangely, eventually excusing himself from the conversation. I ask the girl how she knows him and apparently he's been going to play pickleball on that particular weekday each week "just to see her." Weird, I think, because the guy is married. She then casually drops that they've been hooking up for months.

I confront him about it. He admits to having an issue with cheating and is visibly distressed. I express concern for his wife who I've met and he assures me that she's already aware and that they're "working on it." I leave it at that because I was too stunned about all this having transpired without my notice. I didn't know what to make of it all or what to do so I pretended like everything was ok.

I turned to some of our co-workers who have a longer history with him than I do. Turns out they know all about his proclivities. Apparently he flirts with several women at work and even asked one out despite knowing she also was married, going so far as to hide his wedding ring when he was around her. The guy I thought I knew wouldn't do this, but apparently I didn't know him at all. I started to distance myself from him both socially and at work but manage to keep it professional when we do have to interact.

A few months later he tells me that his wife is pregnant. This is probably what I was most afraid of - that his wife would get pregnant most likely without knowing about his unfaithfulness. This is also where I'm at a loss - several of us are aware, but no one seems to want to inform his wife about what's been going on. So should I be the one to tell her?