How do you deal with all this relentless hate? Have you just grown a thick skin over the years? Have any tips for a teen being bullied?

Thick skin probably has a lot to do with it. As for tips? Stick with being yourself and doing what you love. Teenagers, on the whole, suck. We all mature and move on from the dumb shit, including the bullies. Of all the dumb crap I had happen with people in school over the years, maybe one situation isn't "under the bridge" today and a situation that *I* directly messed up.
Their bullying is temporary (though if you know someone who can help you get it to stop, do it). They'll grow up. Keep doing the things you love doing.