I fucked my wife's younger sister before leaving USA forever

I am 35M married to a 37F. We have been married for the past 15 years. Loving happily with kids. Five years ago we planned to move from the states to Europe permanently. Our last days in the states were coming close. We were meeting up with our friends and family members before we left. My wife has 4 sisters including her. She is the eldest and her 3rd sister Karina(24F at that time) was a little troublesome. They always call her the black sheep of the family. I never looked at her that way. So it was the last day in the USA for us. So we threw a backyard BBQ with our family. My wives all sisters and their partners were there. Karina was single recently broken up. I was aware of that.

During the BBQ I got a work related call and I went back inside the house and I told my wife I will be out for half an hour. The call ended quickly and I was getting back but I saw Karina is in the house and she approached me. And started calling me by my name and said I am gonna miss you, you were such a nice friend and she came closer and I gave in and we started making out. I locked the door and started fucking her doggystyle really hard. Rough doggy fuck. Then she sucked my cock. And then I lay in bed and she got on top and started bouncing on my cock and almost rode the cum outta me. I pulled out at the very last second and came on her phat ass. And then we both giggled and made out for a bit and she started sucking my cock again until I got soft. She said her sister is lucky to get such a cock. After then we cleaned up and joined the BBQ like nothing happened and it always stayed a secret until today.

Hmu to see what Karina looks like.