UPDATE: My (43m) wife (42f) had sex with a former teacher. How do I proceed?

So here is my original post and the update is below that:<br><br>My (43m) wife (42f) had sex with a former teacher. How do I proceed?<br><br>My wife and I have been married for twenty years and we have three kids. I just found out that almost twenty years ago my wife had sex with a former teacher of hers. The teacher had been in his forties at the time so there was a significant age gap. My wife was also in her early twenties, so it wasn't illegal, but it was a former teacher. This was something she never told me, but she told her sister and her sister made an offhand comment to me about it. When I asked my wife about it she admitted it was true. <br><br>I'm not sure how to feel about this. I don't know if this is something I should be mad about, sad about, or if I should just shrug it off. Any thoughts on this?<br><br>Edit: The sister that mentioned it to me is my wife's younger sister. The younger sister was included in the confession her older sister made. My wife's younger sister then mentioned it to me without knowing my wife had not told me. Neither sister mention the teacher's names so I don't know who it was specifically. <br><br>2nd Edit: When I found out, I got very upset and left the house for a while. My wife says she didn't think it was relevant to tell me Because 1. it happened years ago and 2. it happened before we started dating. She also says she only gave consent because she was afraid of not giving consent and what might happen if she didn't. She says she never liked the guy, she didn't enjoy having sex with him, and she doesn't want to ever see him again.