AITAH for keeping a secret from my wife about her past

I now have a secret from my wife about her past

My wife (Andrea, 39f) and I (40m) have been married for 10 years. Our communication is great for the most part, and when we were dating we disclosed our “history” in general terms (number of partners, relationships, etc.).

Andrea mentioned that when she was 22 she had a threesome with her boyfriend at the time and a good female friend of hers, but has never shared details (I’ve asked, believe me, I’ve been very curious). She has said she just doesn’t feel like talking about it, it’s in the past. She only said that her friendship with the friend was negatively impacted because things “just got weird afterward.”

We attended a wedding last weekend where that female friend was present. I connected with her husband, he’s a great guy. He joked that our wives have something in common (testing if I knew about the threesome) and we had a laugh about it.

I mentioned how I’d always been curious about it but Andrea wouldn’t talk about it. He said he knew details - that his wife will talk about it in bed sometimes, in detail, as part of foreplay to make him crazy.

I asked him for examples of details, and he told me everything. They involved things about Andrea’s body and what she responded to and liked and it all checked out. And he told me two things that Andrea did in bed during the threesome that really surprised me - just things that seemed out of character sexually but showed that it was an intense night.

The next day I started feeling weird that I had this information, and I’m not sure what to do with it. Does Andrea deserve to know that I know this detail? Does she deserve to know that her “friend” had told her husband these details? Or do I just take this to my grave? AITAH for keeping this from her? I can’t get the imagery out of my head, I can’t lie.