My mom and middle sister

A year ago my sister had a stress attack and since then everything has changed more than it already was. She was in the hospital for about a week and my mother was very worried, now she treats her differently than she treats me and my older sister.I mean, she favors her more, since I was little I was seen as a child who wouldn't be an example because I didn't like studying at school and my mother thought I wouldn't even make it to high school(im the youngest sister).Now, nowadays, if she starts an argument or talks to me in a bad way, it's all my fault in my mother's eyes, everything I do is wrong, yesterday we had an argument about how I dress because I had to go to the dermatologist and I dressed basic and obviously she didn't say anything to my sister about it, she told her that she dressed nicely (i was wearing a gray top and some wide leg pants) and I didn't understand what was wrong with that, but when I confronted her about how she was favoring her more, she got really angry.She denied everything exactly as I expected her to do and I left it at that until she calmed down because I also had a cold and I didn't feel like arguing.I don't understand why parents favor their children and when they do something wrong they tend to yell at them for things they did years ago even though they are completely different people now. Ever since I was little I was seen as someone who didn't care about anyone's feelings or anything, but what my mother didn't know was that I cried at night when everyone was sleeping until she found my diary where I wrote that I wanted to k### myself (this was a few years before this thing with my sister) and she changed a bit her perspective about me but now its way worse.It feels like my middle sister just likes the attention and everytime i dont keep my mouth shut im still the wrong one.I honestly don't know how i didn't k### myself yet bc trough 2021-2025 i went trough a horrible depression about stress,school,exes and just being lonely and not finding someone who just sees trough me and who loves me.Idk what to say anymore,what do yall think about it?Also thank you for reading all of this ❤️