Someone somehow sent an email from my own domain?

I got a spam message, which is obviously fake, saying how they've accessed my webcam and PC (in which I have a mac mini lmao), and have my browser history. I don't care about that, because it ain't true lol but they sent it somehow from my own domain. I don't have mailing setup on any website, only on Cloudflare.

Does anyone know how this happened? Or if it's some type of parsing?