I had sexual relations with my stepson. (ADN-556)

My husband has a stepson named Yuta. He was initially a well-behaved boy. However, after we moved in together, he started skipping school frequently, hanging out with girls, and his behavior gradually deteriorated… One day, Yuta saw photos of me masturbating. Perhaps it was my fault that caused Yuta's change…? Just as I was thinking this, Yuta pushed me down while my husband was asleep… and then we began a physical relationship.