Is high school as bad as I think it is?

I'm going to be a freshman in about 2 months and I am terrified. I am a girl, so i don't think i'll get physically bullied...but I am still afraid of what people might say. My sister tells me that its nothing to worry about. But she was always quiet and oblivious. When I was in 6th grade I remember the 7th and 8th graders hating me for no reason, and im afraid that the 10th, 11th, and 12th, graders may treat the freshmen the same way. And i'm afraid that my friends may turn on me. And how do I deal with the pressure to to good in classes and still have a social life and not lose my mind? I guess what i'm saying is: i've heard and read about a lot of horror stories of high school, and i'm just wondering if its really that bad? Honestly?