I've been noticing a trend about my sister.

This year my sister went into the same garbage university I do (we dont have a choice financially) , so the people, and atmosphere their are less than I deal I would say (especially some of the men), so ofc I recognize this, but for some reason she has began project this hate and disgust on me? She would say things infront me to stir up reactions like "I wish all men would die", or "I wish I was a lesbian", or "Men are so ugly" , I typically don't respond because I know she'll use the "who said it was about you" response, and I really can't be bothered, but she has started displaying extremely aggressive and cold, situational behavior towards me? She now suddenly "finds me annoying", and I "try a lot to be funny" even though my other sister does the same humor/jokes I do? I suddenly "view my self very highly" and I'm better than her? I spent hours teaching her, and assuring her, and helping her with her assignments, and projects, and I don't expect a thing, all I want is some respect, but it seems like her empty "thank you very much" is just a way so she can reserve me for later use, and my other sister sometimes slips up, and reveals that she has been talking crap about me, and disrespecting me. Other than that, she has been trying to sort of "prove herself" by shouting at me infront of people/strangers, everytime I tell her "no i wont allow you to use my laptop today I need it etc...", and today she told me to eat shit because I asked her to show me a picture of her friend, and then when I remarked about it, she told me it's just "joking" and that Im being sensitive. Ofc I could be just be paranoid, or I could be linking unrelated things, so what are your thoughts about this?