When I Played Mommy Too Seriously at a Patient's House

I'm Dr. Emily Chen, a psychologist who specializes in cognitive behavioral therapy for adults with anxiety disorders. My patients and I have an open relationship where they feel comfortable discussing all aspects of their lives, including personal kinks and interests like DDLG or dominant/submissive dynamics. One day, I found myself unexpectedly stepping into the role of 'Mommy' at a patient's request, but things took an unexpected turn that left me questioning my boundaries. It was during a therapy session when Alex brought up his desire to explore the Dominant/Submissive dynamic in his personal life and how it related to his anxiety around authority figures. We talked about power dynamics, consent, and role-playing scenarios to help him understand better how these dynamics manifest in different aspects of his daily life. One weekend, Alex suggested we go through an exercise where I would assume the 'Mommy' role for a few hours at his house while he pretended to be my little boy. It was meant as part of our therapeutic work to challenge his anxiety around authority and control issues. He said it would also help him feel more secure in his relationships. I agreed, fully aware that this wasn't just an in-office exercise but a real-life scenario with real emotional stakes. We had lengthy discussions about the rules and limits before we began. Everything was consensual, clearly defined, and both of us were adults over 18+ years old, very much in control. However, when I arrived at his place, Alex seemed nervous. As 'Mommy,' I felt a strong urge to protect and nurture him like he truly needed it, which took me by surprise given our agreement on boundaries. When things escalated beyond our set limits, I found myself disciplining him more seriously than planned, like how a real Mom would deal with her child’s misbehavior. I ended up grounding Alex for the rest of the day and insisting he do household chores. The intensity of these actions made me question whether we had crossed an invisible line that blurred therapy and reality too much. While it was clear this wasn’t about childhood trauma or reenacting anything from before adulthood, I still felt uneasy. After a few hours, Alex was grateful but also relieved when the 'Mommy' scenario ended, and we returned to our therapeutic roles. We both recognized that while an exercise like this can be incredibly insightful for understanding power dynamics and authority issues, it’s crucial to respect personal boundaries and not overstep them in the heat of role-playing. So here I am, seeking your thoughts on whether there's a better way to navigate such exercises without losing sight of professional and personal boundaries. Did 'Mommy' go too far? Are there ways we could have managed this differently? What do you think?