Jumping into the thread, answering the questions!
I'm another 5' 9" 130lb person, though I have the advantage of having already been through highschool and the horror of teenage years (trying to go to grad school, but working until that can happen). Martial arts-wise, I went with Aikido, which focuses a lot on avoidance, redirection, breaking people's joints, and not spending energy beating people up. I highly recommend it, especially if you can find a teacher that a) you get along well with and b) who teaches the meditation/breathing side of it too.
I had the advantage of going through a high school with a reasonable proportion of kids motivated to do well and go to good colleges (like Mephansteras), but it was still a public school and there were still plenty of people who didn't care that they were failing.
The first trick is to find the other people who think like you, rather than the people who are satisfied to get B's and C's without effort. There may be people like that at your school, you've definitely found some here. Having that group makes it much easier to ignore the people bothering you for doing well.
The second is that it's not just about working hard and doing well. Ideally, you should be working hard and doing well at something you enjoy. For me, it was programming. For Maggarg, it was being a bassist. Finding something to do, academic or not, will make dealing with the rest of it much easier. At the very least, having a goal to work towards will help with the motivation, since it will give you a concrete answer to "why am I working so hard". If I knew more about your interests (and they were at least vaguely close to the ones I've encountered, which is off in science/engineering land), I'd be happy to suggest some places to explore.
Unfortunately, the world is (by and large) full of retards.
Fortunately, as you go higher up the educational system, and the jobs that that qualifies you for, you run into fewer and fewer of them.