Need Advice - Issues with Living with My Mother-in-Law

I’m currently living with my in-laws, and I’ve been running into some issues with boundaries, particularly around shared kitchen items. Normally, my mother-in-law doesn’t want me using her pots and pans, which I respect. However, I recently bought a nice Staub cast iron pot during Black Friday sales, and when I went to unbox it, I realized she had already started using it—without asking me. I hadn’t even opened it yet, and she just took it for herself.

I texted my husband about it, but he doesn’t understand why I’m upset. His response was, “It’s just a pot… is it really that serious?”

At this point, I don’t even want it back anymore, especially since she’s already lent it to a neighbor.

Has anyone dealt with something similar? How can I prevent this from happening in the future? Am I overreacting like my husband thinks, or is this a reasonable boundary to set?