At this point I would just ignore her emails, it's just upsetting you to read them, and really, there is nothing she can do now. It is too late for her to file a claim with Paypal. She is crazy. Just make sure to block her as a bidder on ebay.
I'd tell her, "Do what you want, but I won't cave in to blackmail. I still have your e-mail telling me you had Gucci fix the bag I sold you, and they certainly would not have fixed a fake. So whatever bag you have now clearly isn't the one I sold you."