I like this guy, but i cant talk to him with out being nervous!!?

I like this guy and i text him every day , he has a girlfriend but he said he still likes people when hes dating. When i asked him if he liked me he said he cant say that he likes me because we never talk in person but he really likes my personality. Every time i see him i look down and walk faster, or avoid him completely by taking a detour.... he is really into sports and i know nothing about sports...how do i start a conversation. we have spanish together but he doesn't like that cl and we never have homework and were not aloud to talk in that cl at all. He sometimes comes to my table at lunch but i get jittery and i only talk to him when he talks to me first. Were really good friends its just an in person thing. How do i handle this weird situation. Btw im turning 14 nd hes turning 15 soon.