AITA for my wife cheating in front of me but saying it was a joke?

Me (M44) and my wofe (I’ll call her Jane) (F43) were at a party together two nights ago. Just for context, me and Jane have been married for twenty months, and there were around 100 people at the party.

I was having fun drinking and hanging out with my friends, but overdid it a little and felt dizzy. I asked Jane to sit down with me on the couch while I drank some water, she said sure. While we were sitting, Jane’s best friend (I’ll call her Rachel) came over and was talking to Jane lol. I don’t know how we got to the topic, but Rachel dared Jane to stick her (Jane’s) fingers in her (Rachel’s) pants? They both were laughing and looked at me for a reaction- I still didn’t feel good and thought they were just goofing around, so I just sat there listening. Jane then said “okay then, I’ll do it”, Rachel unbuttoned her jeans, and Jane started fingering her. That only lasted for a few seconds, they both laughed and high fived, and then Rachel and Jane took off their clothes and started having sex. Even though Jane kept saying “You’re so much better than [me],” I was so stunned and disoriented in the moment, I didn’t say or do anything. Soon afterwards, they broke it off and got dressed, we went home, and I immediately went to bed.

Yesterday, I woke up and remembered what happened, and asked Jane why he would do that. She said it was just gals being pals and doing silly party dares. I mentioned that is felt like cheating in a way, and she said I was overreacting because it was just a joke. She seemed annoyed and shut down the conversation.

I’m home now, and don’t know how to feel. I’m not even mad, I’m just so confused what to make of this. I haven’t told my friends about this yet because I feel kind of embarrassed? Any advice would be helpful because I am just not sure what to do. I consulted this thread! but it wasn’t helpful. Thanks.