What should I do about a guy that has become creepily attached to me?

I’m a fifteen year old girl and I attend a part time school for homeschoolers who want to take some classes that become difficult to teach online. In one of my classes I met a dude. We talked about video games a handful of times, but only ever for like a minute after class. Eventually he asked me for my account on this video game and I gave it to him. We played together and then he asked for my discord, which again I was fine with because most of my friends have my discord.

Over the next few days he messaged me on and off, before asking me to the fall dance. I told him that I could go and hang out with him at the dance but was not interested romantically. This was when I started to feel uncomfortable with the situation. He made several very suspicious comments I will not go into detail on as well as saying things like “People are gonna be like ‘wow the weird kid finally got a girlfriend’. Then later in that week a girl in my class explicitly warned me about him.

I was going to an event that Saturday of the dance, and as the situation put me more and more at unease I decided to stay downtown so that it would overlap with the dance. I hoped that this would stop the constant messaging (20+ messages a day without me replying) yet it didn’t. A week later he brought me a keychain and drawings that he’d made. Reminder: I had only talked to this guy irl for maybe ten minutes total.

He’s also said some very concerning things about his mental health. Note: this is no way undermining people with mental health issues, I myself am going to therapy. The things he said made me see that even a friendship with the guy would be very toxic.

He is also convinced that if I don’t reply it’s because my parents said I couldn’t, even though he just makes me uncomfortable.
I want to be nice and not block him especially since we have mutual friends and the rest of the school year together.

Any advice?

What should I do about a guy that has become creepily attached to me?
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