My evil twin is suggesting that the next time you have a party you send Sue a note specifically stating that neither she, her husband, or any of her friends, relatives acquaintences or coworkers are invited.
Or possibly a restraining order, because I could see them showing up at a party that they weren't invited to on the basis that they heard about it, and hey, the more the merrier.
At least you now know that these people are unhinged, and can avoid contact with them in the future. I'd suggest not answering any more emails and, if you have call display, not answering their phone calls either. They'll just use any excuse to prolong the drama, and not responding is the best way to get it to stop.