i’m in highschool and this person (i’ll call Cat for simplicity) i’m not very familiar with came up to my lunch table with my friends and they were all talking. Me and my other friend went to the bathroom and i usually leave my phone there to avoid it getting taken so as usual i leave it and go. i go to my next class and at the end check my snapchat, Cat had posted a photo of my cat with a weird caption something about poop on my public story. i was very upset but she isn’t even in my lunch so i couldn’t confront her. i talked to my friend who is Cats good friend apparently and she told me that she had some mental issues that no one really knows about and i should cut her some slack because she didn’t know my boundaries unless i told her. I had a very easy password so she could easily get into my phone but i don’t think it was warranted that she go snooping in my phone without me there. i think that she shouldn’t have gone snooping and it’s not about boundaries it’s about basic knowledge to not go into someone’s phone without permission especially without the person there. AITAH for being upset?