Even with the punishments, I've always been prouder and happier when I stood up for myself. So do that anyway. It doesn't stop the bullying, but it does reduce it somewhat and you gain more respect for yourself. You'll probably lose in a fight, but no matter how weak you are, anyone can inflict at least some level of pain on an aggressor.
It's truly sad the way so many kids have to deal with this, yet nothing is ever really done about it.
Unlike you, I would have changed it all. I would have worked out constantly, and made a name for myself as the crazy guy you didn't mess with, because he'd flip out completely.
But as bad as it is, at least take solace that you could go home in peace. Imagine also having a 300lb abusive bully at home that denied you any access to technology, even with your own hard-earned money. My solace was counting down each day to 18, and occasionally sneaking off to public libraries to use their computers for a bit. A lot of my programming I learned from reading books, and the mandatory graphing calculators for math class. At 16-17, I saved up for a laptop, and would use it in the parking lots of retail stores while pretending to be at work.
But as others are saying, it gets a lot better. I make $70k/yr now, total household income is 120k/yr, have a nice house and cars, and all that. The worst I have to deal with anymore are the occasional trolls online.