My boyfriend and I have known each other for a while, so I often go to his house to stay. My boyfriend has a younger sister, Karen, and although we often fight, we are really close. Today, my girlfriend said she was going on a trip with a female colleague in the company. I didn't pay attention until I suddenly discovered that she had gotten into another man's car! The angry neighbor was brought home to find Karen sitting in front of the door. It turns out he had realized this a long time ago but wasn't sure. At this point, Karen confessed her feelings to me. I didn't believe it so I joked and asked her to take off her panties and spread her pussy in front of me. Suddenly Karen did it without thinking. Angry about my girlfriend, I took out all my anger on Karen. If you are unfaithful, neither will I. I treated Karen very badly, blindfolded, handcuffed, strangled …