I [14F] rejected my best friend [16M] and he won't stop asking me to talk about it

Basic stuff, my best friend Austin confessed to me, and I said yes because I felt a lot of pressure and stress at the time. I told him a day later that it was pure pressure and that I was sad to say I didn't share his feelings but we could stay as friends. I told him specifically not to bring it up again, and that I needed some time to get rid of the discomfort the confession brought me. He said it was fine, and I avoided him at school.

I sat down at our groups table. He kept looking at me the whole time but I tried my best to ignore it. Keyword, tried. I kept stuttering the whole time I talked because I could literally feel his eyes on me. I kind of glared at him for a second as a signal to stop. He didn't.

Now, it was at this time when nearly all my friends decided to leave to talk to the counselor. Four stayed, two girls, Austin, and me.

I didn't feel too nervous, I mean he wouldn't try anything in front of our friends right? Wrong. He scooted closer to me until he was in my personal space. I felt so uncomfortable and I legitimately wanted to crawl inside a hole and die. I was VISIBLY shaken.

That's when it started. "Can we talk?" "Look, I just want to say something." "Do you want to talk about it?"

I told him I didn't want to talk, and I reminded him of what he said. He didn't care. And the two girls were too caught with each other to see me at the brink of tears. He kept asking and asking. He wouldn't stop. I eventually stood up and started walking away, and guess who followed? Austin.

I told him that I didn't want to talk. He kept trying to force it on me. I told him I wasn't comfortable and he just brushed it off. The bell rang and I ran to my class, which thank God didn't have him in it.

I just got home and he won't stop texting me. I don't know what to do. I told him to stop but he won't.

Reddit, what do I do?

tl;dr: I rejected my best friend and he continues to obsessively ask me to talk about it even when I've told him countless times to stop.