Come back to me in ten years mate, and tell me it still bothers you. I don't say this to diminish either his commentary or your age....I say it because, I can not recall a single issue I had when I was 15, that actually bothers me today at 38 years of age.
Toughen your hide, steel your resolve and ignore the ignorant, my friend. If you live to be 80 and this is the biggest issue you're ever confronted with, then you have truely lived a charmed life.
My best advice to you? Concentrate on YOU and YOUR life mate. The older you get, the more halfwits you're going to encounter. If you let them get to you.....well, they've got you beat haven't they?
^this +1000000.
This kid is doing this because he enjoys the reaction he gets from you. It's fun to him. When you stop reacting, it'll stop being so fun.
I had very similar experiences to you at that age, and I fully ally myself with PFOG's comments. 23 years later, I've made a successful career, am married to a beautiful woman, want for nothing, and play music semi-professionally with critically respected musicians. Most of the guys who bullied me in school are working dead-end jobs in the same small town we grew up in, and if they did play instruments, few of them do anymore. I actually ran into a couple of them at my 20th reunion, and it was interesting to see how adult life has humbled and mellowed them.
And seriously, if this guy gets you this worked up, it's not going to be easy for you at all trying to make it in the music industry. People there, by and large, are much less interested in your emotional wellbeing than they are in getting stuff done to standard, under budget. They can be prickly, abrasive, and plain mean. The trick is to roll your sleeves up, work hard, and let occasional personality issues go.
As for right now, I say ignore the guy, let him crash against your brick wall of reserve, and let him overstep to the point where it's him getting in trouble. Because right now, he's getting everything he wants in life from you.