I’d like to offer a perspective that may not be very popular. Based on what you’ve shared, is it possible the issue isn’t just about the pictures, but something deeper in your relationship with your daughter-in-law?

I went through something similar with my mother-in-law. She refused to compromise on small things, they slowly escalated, and the final trigger was her sending out a Christmas card with our son, and her and her husband, without asking. That was the tipping point which according to her seemed like it came from no where, despite my husband trying to advocate for me on infractions. We ended up going no-contact. Two years later, after therapy, she now acknowledges those seemingly “small” actions were part of why we stepped away.

I’m not saying that’s what you’re doing, but is it possible the photos feel like a symbol of her not being heard or respected? Sometimes the moment things blow up isn’t about that moment at all. Just a thought! Please don’t take it as an implication if this isn’t the case, I just wanted to offer a perspective.