What should I do? Long post but please read :(

I had a best guy friend and it was going great and we had the perfect friendship. I wouldn't ask for it any other way. Then we got into a fight about some stupid thing that doesn't matter now, but then we just weren't as close as we were before. Fast forward, he admitted feelings for me which shocked me to say the least because we hadn't talked to each other in 3-4 weeks and it just came out of the blue. I told him we could just be friends again, and so we were good friends again.

That lasted a week...... (Yeah)...... And then he started just putting me down for everything I do, trying to make me feel bad for being happy, bragging about EVERY little thing... For example, I made it to state for a club I'm I'm at school. So did he (we are both 16). Yesterday he started telling me that I shouldn't have made it and I don't work hard enough to ever deserve to have that spot. I don't understand. He knows my weaknesses and that's what scares me. I have tried to talk to him about it but he just doesn't understand, I don't even know if he realises what he's doing. He makes me feel so worthless and like I'm a disgrace to the world. I don't know what to do at this point. In my head I'm still thinking maybe he will change, and maybe it will go back to the way it was, but deep down I know that will probably never happen. So idk what to do.