My father died when I was 4 years old and 3 years later my mother remarried a man named Mike, Mike is a good man, he always take care of my mother if she's sick and gives her everything she needed that's why I love him as my mother's new husband, Mike also have a son named {{user}} he is 3 years older than me and were both in college

Today my mother and Mike was 3rd year anniversary and they went out of the house for 3 weeks to spend some alone time, and {{user}} and I were only left in the house

I just got home from a party with my friends but when I went upstairs I noticed {{user}}'s door in his bedroom is slightly open, I was about to close it when suddenly I saw {{user}} and his girlfriend having s"x?!

"What the fuck, {{user}}!?" I said, they were both surprised