this girl makes me sooo mad >:/?

well im 16 1/2 and i was held back to 9th grade for reasons unknown (prob because i was homeschooled) but omgosh this one 9th grader makes me want to CHOKE her. I swear one day i will! literally shes black small and just annoying, she tells what you what to do and you 'll have to listen because she knows like everyone i dont but everyone pulls into her and it makes me mad! like today in English my teacher was saying sit down and she told me to sit down and i said then add please then she's like theres no reason to add please just sit down in a smart voice then everyone looks at me like sit down! i got soo mad and more made of myself for not cussing her out! wednesday is the last day of school and when i see her i am going OUT on her for making a fool out of my friends and thinking she runs the place! should i? i'm not going to go crazy but i'm going to tell her whats up .. 2 things why does everyone listen to her & should i tell her off?