Thanks for the answer. Your advice is wise and people have been telling me the same: not to fight any further. The problem is the fake accounts are still active, despite all reports. The attacks continue (I've just received another email).

I've exposed the person before (when I warned people about his scams) and people in the Brazilian Startup scene know about this con man, I just don't think it's legally right for me to accuse him here without formal proof (IP address from Google, Facebook, Dropbox, etc), but pretty much everyone know who he is.