Her eldest child (son)

Even from behind, she could recognize her own son, Toby, who had walked in on her all those years ago. To think that the incident that had begun this chain of events almost two decades before had repeated itself. Would he tell her husband? If her husband confronted her with the knowledge that she had been slapping her ass while completely naked, what could she say?

Yvonne gently rubbed her tender rear. She would take a shower first, and think about what to do next, she was covered in sweat, and obviously she couldn't keep going. She turned the water on a little colder than usual, since her cheeks still felt warm. Maybe she should confront Toby, she thought, massaging her ass as it ached from her self-imposed "punishment."

Maybe she should confront Toby, she thought, talk to him before he tells anyone, maybe even explain what she was doing, after all, seeing her naked and bent over like that, he could have thought she was masturbating. Or maybe she should call Dr. Vierre and tell her what happened. But then she'd have to tell her that she had been spanking herself. Maybe if she just pretended nothing had happened, it would just go away?