If your account of what you said, sent, etc. is the truth, then YOU should contact the police and file a report for extortion. This sounds like blackmail, pure and simple. This person is just betting that the questionable behavior he lures people into will prevent them from ever coming forward.
From what you describe of your behavior, it was certainly stupid and narrowly skirting danger, but you didn’t cross the line into committing a criminal offense (again, presuming you are being completely truthful). So, I would advise contacting the police and reporting this predator for extortion.
If you are being a bit less than honest about your actions in this email exchange, then take this as a $400 wake-up call and seek help from a mental health professional regarding how to deal with your pedophilic tendencies.

