My mother-in-law let herself into our apartment while we were out town

We gave my husband’s mother a spare key to our apartment strictly for emergencies or if she needed to feed our cat when we went away for long trips. We explicitly asked her to always text us before coming over. This weekend, my husband and I went to a lakeside cabin just two hours away.

Yesterday afternoon, I checked our indoor pet camera app to see if the cat was eating, and I saw my mother-in-law sitting on our living room sofa.

She wasn’t checking the cat. She was slowly going through our mail organizer on the counter, reading our bank notices, and then she walked into our bedroom and started organizing my closet. When I used the camera’s speaker to say, "Hey Claire, what are you doing?" she jumped, looked incredibly guilty, and instantly disconnected the camera’s power cord.

We drove back early and confronted her. She claimed she was just trying to do a "deep spring cleaning" as a nice surprise for us because she thinks I’m too busy with work to manage the household.

My husband is defending her, saying she’s just old-fashioned and wanted to help, but I feel like my privacy has been completely destroyed. I demanded she return the spare key, and now the entire family group chat is calling me ungrateful. Am I overreacting here?