My sister and I are pretty close, we're 19 and 22 so similar in age and share pretty much everything with each other. A few months ago I was sorting out our stuff in our shared room at home when she was abroad and I was packing away her old university notebooks. One of her notebooks wasn't a uni one so I flicked through the pages to see which box it should go in and realised it was a diary. I had no idea she kept a diary and the words I'd picked up were about am event she'd told me about in detail so I was curious as to what she might not have told me. I almost decided to read it but the first page had "diary - PLEASE don't read" on it so I didn't because I know I'd be upset. I know it was probably more for my parents and brother but I still didn't read anything because of it and just put it in with her university stuff.

Today my sister was going through the box and asked me why her diary was with her uni stuff and started accusing me of reading it. Yes, I was really curious and almost did but after seeing her privacy note I respected it and didn't read it. The only thing I saw was when I flicked through and it was just a person's name and a country name which was enough to tell me it was a diary. She finally believed me but she's still kinda skeptical and upset about it but I honestly didn't read it. Her main reason for worrying though is that she said she would read mine if she found it hahaha I don't have anything personal enough for that to bother me but it's a bit odd she'd read mine but be angry and upset if I read hers.

What would you have done?