Ichi, you're never going to get justice here, if that's what you're looking for. You're never going to get it anywhere for that matter, because it really doesn't exist except maybe as a plot crutch in comic books for dudes wearing panties to wrestle around while strategically using their capes to hide mutual erections. Best to block him so you never have to see his posts except in quotes, and store this away as a lesson for future reference. People online and in real life are going to fuck you every chance they get and not give a shit, then they're going to laugh about it, and unless you have the means to put yourself within arm's length of them there's absolutely nothing you can do about it. If you're lucky you'll meet a few online who aren't like that. For the most part, I'm lucky in that respect - my podcast partners are awesome, better in a lot of ways than my real-life friends (who only tend to show up at my doorstep when they want me to do something for them, I'm double-fucked there because I paint AND I own a truck).
When I first started my business I loaned my accountant (I thought I was going to make enough money to justify paying one $75 a month, hahahaha) $1200 for rent/bills, because she called me up crying one night saying that her roommate/boyfriend had skipped town/written a bunch of bad checks/used her cards, pretty much wiping her out. *GASP* PLOT TWIST! Turns out she had a taste for the expensive kind of drugs, and she fucked off with my money and all my paperwork after hemming and hawing a couple weeks when asked about starting to pay me back. I had to track her down through her sister, call her from a friend's house (caller ID), and make some vaguely thuggish threats just to get my paperwork mailed back to me. Then I took her to small claims court, where she never showed up and I stood in front of a judge who told me something I already knew - I was never going to see that money again, that'll be cost of court please. As the cherry on top of that Fuck You Sundae, I had a parking ticket waiting for me when I left the courthouse. About a year or so later I saw her pulling out of a Circuit City parking lot, driving a nice new SUV while I was sputtering out in a 1978 Chevy van which had holes in the floorboard big enough to do the Flintstone brakes with.
I think about that $1200 from time to time, whenever I could really use it, like two weeks from now when I have to write a check I hope I can get enough money passed through the bank system to cover by the time it arrives. But I'd say the lesson was a little bit worth the cost, because I've never made that much of a dumbass out of myself since then, and I've had plenty of opportunities to do so. I don't even really remember what she looked like nowadays, just the lesson and the money.
Anyway, just a little friendly advice, remember the lesson and forget the teacher. You're just wasting time and energy which would be better spent elsewhere.