I went thru a dark period in my life when I allowed what other people said about me to really pierce me to my SOUL. I learned thru Al Anon and counseling that I didn't need to allow other people to define me.I got to define MYSELF. It took a lot of good and positive self talk and a fair amount of journaling, but today I can honestly truly say that what other people think about me is none of my business, and what other people say about me is just their opinion. It no longer defines me.
I would guess this young man and others will stop when they see that their words no longer have any power to disrupt your life. Until that time, I think you should go to your principal or other authority and discuss the ramifications of bullying. Most schools have a zero policy on that.
BIG hugs
Cats