What to do about this girl in my homeroom?

Okay..So there's this girl in my home room, her names' Ali, and like I was nice to her as much as I could be, she's really annoying though, and when we were supposed to be working, she would always try to be talking to me, or asking me for the answers, to which I would tell her that I was busy, and that I couldn't, and she would get all mad, and call me mean. At first, it bothered me, but like now it doesn't, and I don't talk to her at all, but the other day in gym, my friend and I were talking, and this new girl, Hannah, walked up to us, and told us that she was the fastest in the cl. I know, 7th grade, I shouldn't be this immature, but I take things wicked offensively, especially when I have low self-esteem, and running is one of the things that I do best at, and I rolled my eyes to my friend, and was like 'Oh wow.' And then it wouldn't have even bothered me, but then Ali walked up, and was like 'Yeah..I thought you two were the fastest, but Hannah is way faster than you, obviously.' And that made me pretty mad. Like seriously, she had the nerve to do that. I'm one of the fastest in the cl, and Hannah is wicked slow, not trying to be mean or anything, but she is. And today, in study hall, towards the end, Ali invited Hannah over to our study hall, and she came over, and she looked at me, and she was like, 'Who's HE.' He. She seriously called me a guy. I just looked at her, with my, 'Did-you-seriously-just-say-that' face, and she's like, 'Oh, whoops. She.' With like no regard. I don't dress like a guy, or look like I guy. It's not that I have shoulder length hair, or wear make up or a cami showing under my shirt. Seriously. And Ali was like, 'Oh. Her? She's Xxxxxxx.' With a snobby tone to it. And I was like 'Uhm okay?' And I walked over to my friend to talk to her, but as I was walking away, I heard Hannah say, 'Is that the b!tchy one? She seems like it.' And I mean seriously. Seriously?! Stooping that low? I'm not a mean person, to anyone. But like that stuff just makes me mad. And Ali was like, 'Yeah that's her.' Like I couldn't hear or anything. What should I do about them, I don't want to deal with this my first year in Middle School. l: Help Please?