Caught

My wife Amy and I went to a Holiday party at a coworkers house. We were all having a good time, drinks flowing and plenty of food. Amy was talking with a bunch of the wives and most of the men were watching the football game.
I needed to take a leak and headed to the bathroom in the rear of the house. When I came out, one of the other wives was waiting so I stepped to the side to let her enter. I never even got her name, but she was obviously a trophy wife. She pulled me into the bathroom and basically wrapped her arms around my neck and kissed me. Shocked, I pulled away and she told me to keep quiet, that Amy said it was ok. How did she know Amy’s name?
She grabbed my junk through my pants and told me she heard I was a good fuck, and she needed to try me.
I don’t know why I believed her but she turned towards the mirror, bent over the sink and pulled up her skirt. I went for it. We were fucking for a few minutes, and I was trying to be quiet when there was a knock at the door. We hadn’t finished, but she said she’d meet me later.
When she opened the door, there was Amy. Fuck, she was pissed and started screaming at me, calling the other girl all kinds of names before she stormed out and took off with the car.
She won’t take my calls, hasn’t been to the apartment and I think I really fuckedup!