The time I met my gf’s best friend [MFF]

TLDR; I met my gf’s friend Samantha, the three of us sleeped in one bed, but I’m the only one knows ehat really happened at that night, and it involved the three of us
I felt ashamed at first but years after thus is one of my favorite acts
100% true story I’ve been waiting to let out, names has been changed

This story happened more than 10 years ago, I was 20 years old, pretty built up as a professional swimmer, about 5’7, semi long blonde hair, hazel eyes and a masculine figure

I have been with my (ex) gf (let’s call her Maddy) for almost a year
Maddy was 18, still in highschool so we met mostly on weekends
She was about 5’0, dark hair, dark eyes, nice and curvy body, about C cups, and a very nice butt
She was actually my first sex and I really loved her deeply
We went on vacations together, and most of the times met at her parents place