I (32F) share custody of my 5-year-old daughter, Lily, with my ex-husband, Mark (35M). Mark recently started dating Emma (28F), and they’ve gotten along well. Lily enjoys sleepovers at Mark’s, and I’ve always thought Emma was great with her.

However, today, Lily casually mentioned, “Emma used a sponge to scrub my back” during a bath. I was taken aback. I’m fine with Mark handling baths, but Emma bathing my daughter felt too personal. I called Mark, and he brushed it off, saying Emma was just helping since he was cooking. I felt it crossed a boundary, and Mark disagreed, saying I was overreacting.

Later, I spoke to Emma, and she was surprised, saying she didn’t think it’d be an issue. She loves Lily and was just trying to help. Now, Mark is upset with me for “blowing it out of proportion,” and Emma is distant. Did I overstep by setting this boundary?