When I went back to my parents' house, my sister-in-law was cleaning in a miniskirt and her panties were visible through her stockings. I got an erection. Unable to hold back, I quietly jerked off, but my sister-in-law caught me. I thought she would drag me away or get angry, but instead, she was very interested in my dick. My sister-in-law had been in a sexless relationship with my brother for so long that her frustration reached its limit. Their sexual desires aligned perfectly, and they would sneak touches or oral pleasure from each other while my brother, mother, or other family members weren't looking. However, they couldn't hold back any longer and crossed the final line, having sex when the family was out. I gave it to her hard with ghostly pistoning in the hallway, kitchen, or places that make my sister-in-law blush.
