Stressed and depressed because of school?

I feel so stressed and depressed because of school. I'm now in my middle high school year. My school has this system ; there would be 6 class for each year, 5 normal class and 1class for smartest students in every year. I've got 3rd rank at first year, in normal classes, which means i would be in that smartest class at second year. Now i'm on the second year.
I thought it was gonna be okay, since i passed the first year really well. But i was wrong. I can't keep up with the lesson, esp physics biology and math. I already work hard on them, but still, i'm not better than the rest of "smart" people in my class. I always get 7or 8 (we use number, max 10) but in my class, it would never be enough. Finally, i lost all my motivation to study because all of this smart people. In 1st semester on my second year, i got rank 17th with the average score of 8, 4, and in the normal class, the 3rd rank is in the same average score with me. At first, i want to cry but then i know i got a second chance to fix my rank. Then i work hard at the 2nd semester, and it went really well until the mid of my 2nd semester. I really lost my motivation again, because i study hard for one exams but i only get 8 and almost all of my friends in the class get 9. I'm crying, i feel stupid in the middle of them. I compared my score to my other friends in other class, well my score is higher than them. But it would never be enough. I'm now doing my final tests for 2nd semester, and i already failed on 3 subjects: accountant, physics, and civic education. I know that i wouldn't get 5th rank (that's my target for 2nd semester) since i already failed on 3 subjects. I'm terribly at math and rest of the students too, so i don't really care about it. I really want an iPad or iPhone for my birthday present that would be happen around summer. I think my parents would buy it for me if i have good rank in my class, but i'm not, and my parents will be mad at me and i'll not get what i want. I cried at midnight thinking that i'm not good enough to my parents, and possibility that i would have the last rank in my class for this 2nd semester.
i also hate my friends because they're smart, they're dilligent and they have what i want
i know its too much and i'm such a pathetic for hating people because they're smart. I think i already tried my best but this really makes me depressed, and i'm hating myself because of it.
i don't know what should i do! I can't tell to my sisters because i'm not close to them, and my family is having a "angry" genetic, so they easily mad, angry, and yelled to something/someone.that's why i can't tell anything to my family.i'm stressed, depressed, emotionally drained and angry because of this whole thing. This is stupid. I just want to die or run away from home, or if i could go back, i would tell my teacher not to put me in this "smartest" class.

There will always be somebody better at something than you. Fact of life. Get used to it. And just do your best. That's all you can do. And nobody can get mad at you for doing your best.

Also, try not hating people who are better than you. That will ruin your self esteem, well, actually, sounds like it already has. Just try to find your strengths and focus on them, and if you have weaknesses, ask for help. Not sure why you feel you can't talk to your teacher about it, but that's what they're there for. So go talk to them. They get paid to help you. You should be proud of being put in the smart class. You were used to being a big fish in a small pond and now you are a smaller fish in a bigger pond. If you think middle school is bad, just wait until you get to high school, then college, and if you decide to go to grad school - well, let's just say the curve is the antichrist.