This is not the first time I have been to my mother-in-law's house, but I still feel incredibly nervous. Coincidentally, my sister-in-law and her husband are also visiting. While I was in the bathroom, I accidentally saw my sister-in-law naked; she is truly beautiful, and her alluring body made me unable to think straight. The next day, when everyone went out and only my sister-in-law and I were at home, she seduced me. Although I knew this was wrong, I could not resist her allure. We made love while everyone was out, and even when my wife was sleeping next to us...