Four years after marrying my husband, we moved into his family home with his father. I got along well with my father-in-law and lived happily, except that my husband’s passionless sex left me frustrated. One day, while masturbating in an empty house, my father-in-law caught me. He seemed sexually frustrated too, and when he approached me, sympathy got the better of me and I gave him a handjob just once. That single incident opened the door, and before long he came looking for me again.