Horny step-sister gets a rough ride from me

My step-sister is a total hottie, and I've been wanting to bang her for years. Her boyfriend is always traveling, so when he's away, the rules don't apply. One day, she caught me watching some porn and she decided to join in. She's not really my sister, but my girlfriend's sister, which makes it even hotter. I've been dreaming about this moment for so long. She gave me a mind-blowing BJ and then we went to my room to have some real fun. My mother-in-law was at home, but we didn't care. We were too horny to worry about anyone else. We had a wild and rough sex on my bed, with her riding me like a pro. It was the best sex of my life. I hope my girlfriend never finds out, but if she does, I'm sure she'll join in too.