You don't wake up in the morning to receive love, kindness, and service.

I don't expect this though. I expect family members to treat me with respect though.

but don't withdraw completely. She's 18. Chances are she will eventually move passed this and regret it, and you can mend your relationship.

My parents say this but it's so frustrating. Being younger doesn't excuse someone from disrespecting others. They have always let her off easy and this is why she has become a bitch to me, because she knows she can get away with it. A part of me really despises my parents for their favouritism. It really makes me hate them.

Also, what if she never learns? Some people stay unaware forever. Some people never learn. Do you think I should talk with her again or write her a letter? I don't know how I can get through to her and enlighten her. But I also fear any more interactions with her. The way she makes me feel is dreadful :(

all you can do is be there for her if she needs you, love her when you interact with her, and let things run their course.

I agree with letting things run its course. I hope she will reflect one day. However, it's near impossible to love her. I will accept her for the terrible person she is now and love the past version of her but I can't love someone who's like a devil

There is something that happens subconsciously when you treat someone with genuine kindness (with no hints of passive aggression) and they treat you with malice.

What do you mean by this? Are you saying if I am genuinely so happy to her, she will rethink her actions towards me? I doubt it though. I'm not ecstatic when talking to her but I keep my tone of voice pleasant (no passive aggression at all). I don't know if you've experienced someone being a total bitch to you when you're treating them with respect, but it's completely distressing. It's distressing to consistently look at their angry face, hear their irritated speech when you're being kind the whole time. It ruins your mood right away and you have to try hard to think happy thoughts and restore your inner peace.

The fewer excuses you give her to actually treat you poorly, the quicker she may realize it's unfair

How do I do this? Should I call her out and say, "stop speaking in that tone and looking at my angrily!" I really dread interactions with her so I really don't want to confront her. I tried that in the past and she doesn't change at all.

Also how do I deal with the extreme anger when I continuously see her being nice to other people? And other people say she's "kind". I feel like going crazy because others don't know how evil she is!!!! Ugh it's so unfair!!!