TW Blackmail help!

Last September I entered an agreement with a man that lives in a different state. I’m 18 and he’s 32, we agreed to a “cnc blackmail” if you would. I trusted him a lot. The agreement ended in mid November. We still kept in touch, he was very kind to me and we sort of became friends. Come December, I started dating someone and he tried to message me a few days ago. I told him that I was now in a relationship and out of respect, we shouldn’t talk anymore. He did a total 180, I haven’t sent a nude to him since November. I don’t know what to do.

As a last resort, I texted his friend. During our agreement, he gave me his friends phone number and told me to “accidentally send a wrong number nude”. It was faceless, he doesn’t know what I look like. I told him that I wasn’t out for revenge, I don’t want to do anything to set off my threatener, I just wanted him to talk to him about it.

And before anyone in the comments decides to talk about how much I brought this onto myself

and how trashy I was, I KNOW. But what’s dorm is done and I just need advice on where to go next.

EDIT: I turned 18 August of 2018, so I was of legal age for all of this. And thank you guys for your advice! I wasn’t sure what I could do legally but I’ll definitely look into it more now. Thank you.