Wife made out with a stranger in a bar for a dare

It was a girls night. As per her they were playing truth or dare. She was given a dare to kiss the next guy who enters the bar. The friends mentioned the dare as 'a kiss' meaning she could have just given a peck on the cheek (and which would have been fine with me as a part of the game)

But she went in for a full passionate make out with a guy probably 10 years younger than us (we both are 34). Then that guy used tongue so she used tongue too. They apparently did it for at least 30 seconds. I'm pretty sure that guy would have got an erection then and jerked off after going back home thinking about my wife.

My wife didn't even tell me this but I got to know this from one of her friends husband who is also a college buddy of mine. I confronted her and she tried to brush it off as just a game and didn't show any guilt or remorse. She sensed that I was upset so she initiated sex to get me to shut up. So we had sex and then slept for the night. This was 3 days ago and now I don't know how to bring this topic back to discussion again?