I'm starting to hate my best friend?

So, um, I'm starting to hate my best friend. I mean it's not as serious as hate, I'm just starting to dislike her a lot. Me and her have been friends for 4 years, and those 4 years we've been friends, I have always felt unimportant with. We have 5 people in our friend group, and three of us are in the same class. So, me and her have always been in the same class, we're desk mates. Everything is okay when we're in class, but when we're out of class, our with other friends, I am immediately forgotten. I always felt like she only talked to me when I was only needed by her.

Now, we have changed our seating styles, and we sit in threes. Me, the other girl in my friend group (she actually recently joined us) sit together. Of course, she requested to sit in the middle of us, claiming that sitting in the corner was stuffy, and made me sit there. Since we've changed this sitting style, she would NEVER talk to me, unless it was something she wanted to know, or needed. She now only ever talks to the other girl. Am i just jealous and paranoid? Although I was pretty hurt, I still kept quiet, I didn't want to cause any drama since I hate it.

I'm also quiet worried for her, since she's kind of a lazy bum. In my country, We have a huge test where all of us have to take at the age of 17, which is this year. She skips school whenever she feels like it, there was a time she skipped a monthly test. The test was 3 weeks long, she had a competition during that time, though it was only 2 day of the exam. She claimed that she too tired to study, when I tried to advice her, she got pissed of and said I didn't think of her needs and called me a bitch. I have always been super patient with her, and I think she takes advantage of that. She wasn't like this before, I think she's changed, or maybe the one that's changed is me.

What actually pushed me to write this post was this. She said she would be absent the following Friday, and the day before Friday, our teacher informed we had do redo our accounts project. It involved calculating again, balancing again, retyping again, the reprinting. A weekend wasn't enough to finish my own, but she expected me to do hers. After the teacher said she would guide us how to redo it that Friday, she immediately said, "Doesn't that mean you have to do mine too?" No asking if I was free to do it for her, she expected that I would do it for her, do doubt.

I mean I would, if I would handle my own, but I couldn't I said that I wasn't free that weekend, and the teacher even said she could plan a day after school where she would guide her personally, but she still insisted I do it for her, claiming, "I have to work part time on the weekends, do you? All you know how to do is spend your parents money, you're so useless. What are so busy about?" Her words hurt me, because I don't use my parents money a lot, only for educational fees, I don't even shop for clothes. I told her I had to do my own, and she got mad and started throwing stuff and hitting tables. She even bitched about me with the other girl.

This wasn't the first time it happened, one time, we were doing a language project so we met up. I had to type it and I forgot to bring my pen drive, so I used hers. I couldn't finish so I brought it home, once at home she texted me , "My accounts project is in the pen drive and it's due Monday, help me finish it." She could do it on her computer but when I told her that she said she absolutely needed it, and even blamed me for not finishing our language project in time and having to take her pen drive home.

And here's another thing that happened, she didn't finish her essay that was due that day, and I was doing some math, which was also due that day.She's weaker in language, so every time she writes essays I would help her. So I explain to her while doing my math, then she tells others that it was my own fault by doing questions while teaching her.

She has always had a tendency to hurt people with her words, usually unintentionally, but lately it's getting worse. I'm not sure if I can stay friends with her any longer. I love her a lot and still care about her, but being friends with is getting tiring.

Maybe I'm just a fake ass bitch? Am I just jealous? I don't know, please give me some advice!

By the way thanks for giving time to read this post, even if you don't reply, you're a pretty little unicorn.