If I could, I´d kill him

I´ve been swimming for 11 years now. And in my group there´s a boy, who´s been bullying me for last 3 years. The reason he does this is pretty simple. We´re in the same grade and I have better marks, I am smarter than him (I think more logically and I think of consequences of my actions). First 2 years I took everything he said seriously. My confidence was really low and wanted to stop swimming, though I love this sport, I wanted to end because of him.
A year ago my mom noticed that I am always late for the practice and I come only when the couch is there, because this boy isn´t bold enough to say anything in front of the couch. My mom made me talk about this problem with her and the only solution she gave was to ignore him. And I did.
For a year now I´ve ignored him but it doesn´t help. He still bullies me, sometimes even more than before, becuase I don´t notice him. Every day I ask God to give me patience, because if He gives me stregth, I´ll kill this boy. Seriously.
I never wanted my couch or my mom to interfere in this. But my mom told him about this like a month ago, when all this s*it he´s doing got even worse. He and a few other guys stole two my swimsuits, a towel and my drinking bottle, which I found later with (probably their) piss in it. Would you consider this normal? And this thing with the stolen things happened a week after my couch talked to them about this bullying.
I´m going through this every day at the practice, my only good luck is that I have a few really close friends at school, so I don´t have to deal with this even there. But I won´t stop swimming just because some boy hates me. There´s one very good song about this from Lilly Allen - F**k you.
https://www.youtube.com/watch?v=KUHqFhnen0U