Wife sharing her sexual past with a college guy [MF]

So this has been a build up for a while. My wife and I both met when we were 41. Second marriage for the both of us. We have been married for three years now, together for five. Up until only a few months ago, I never really cared about her past escapades. Mostly because she is a little reserved sexually. My wife is definitely the person that likes to keep the bedroom in the bedroom. 

Back in September, after a party at our house and some drinking. My wife and I found ourselves talking about our sexual pasts. And to be honest, nothing with hers really stood out. No crazy numbers she has been with etc. Other than that, I just threw out, have you ever been in a threesome or multiple people at once? She got silent and said well not really. I started to press her as that wasn’t the answer I was expecting! At the time all that I got was, it was during her divorced years. She shut down at the time and I stopped asking.