Yu Shinoda committed incest with her husband's beloved son

Yu Shinoda committed incest with her husband's beloved son. Yu Shinoda has married a new husband and this man has a rather grown-up son. They lived happily together until the father went away for a few days and left his son with Yu Shinoda. They developed feelings, and somehow they had incestuous sex with each other, and whether this story was discovered by anyone later or not.