I'm dealing with a stalker and don't know what to do. Can you help?

I'm dealing with a stalker and don't know what to do. Can you help?

For context, I'm 16 and in my last year of high school (female). The stalker graduated high school this year and isn't in college now. Over the summer I was friends with this person to some extent, but I realized they were a pretty bad person, so I cut off contact and went on with my life.

One day they showed up at my house and my friend's house separately and waited outside. I was scared since I'm a minor and was home alone. They kept calling and messaging me on my phone. Eventually they came through our gate and pushed a letter under the front door even though we have a mailbox. My friends got very angry and sent them a message telling them never to contact us again.

After that, they threatened me twice through TikTok messages, saying they would call my parents and tell them what I did (I didn't do anything), or show up at the local SM or my church and make my life hell. I'm sure it's them, but they're using a new name on TikTok, so I don't know if I can prove to the authorities that they sent it.

I also noticed they keep following my school's club, especially on social media, even though they aren't a student at my school. I had told them that my friends and I are members of that club. They're also still following my social media. Once I reposted a club post I helped make, and the caption had my name on it. The following week, a false claim appeared on our school's anonymous "freedom wall": "Don't join [club name], one of the officers has S.A (sexual assault) allegations." But everyone at school knows my friend, the club president, is the only officer, so whoever wrote that definitely isn't a student at our school.

Recently they've also been getting close to my friends and schoolmates, spreading things about me to turn them against me. They've even been sending private recordings of conversations with me to schoolmates, conversations I didn't know they were recording.

Honestly, they don't have much leverage over me, and I don't think they'd go so far as to physically hurt me. They're just actively trying to ruin my reputation. The worst things I've done are make some bad jokes and talk badly about a few people. Beyond the obvious, like cutting contact, what can I do? Is anything they've done illegal? How do I apply for a protection order, and would this be enough grounds to get one? I'm worried that since it's a new-name account, people won't believe me even if I show them the threatening messages.