To the original poster- ttm269:
Some GREAT advice here from all these posters. Be cautious in where you meet and what contact the escort has for you. On a first hire - ALWAYS meet in a public place. Use a burner phone number not easily traced to you, and pay cash.
As far as him extorting you, I agree with the others - he won't continue to pursue you. He WILL however, if you feed into this. IGNORE it. If he does, tell him you've made a police report, and if he wants to post something online, his IP address is traceable. Just ignore him, as hard as that is. Something similar happened to me a while back, and by ceasing to "feed" it, the problem just went away.