Isn't it interesting that when someone tries to harm you they end up helping you? I'll bet if they knew, they'd stop causing trouble and meddling. I certainly wouldn't want that.
It's like a bad review. On the surface, your work has been slammed -- HARD. It's a blow to the ego and to everything you thought you had done. Don't take it like that. A bad review causes talk and talk causes interest which ends up in sales. Take a bad review like a free marketing push that will put your work higher up in the consumer's consciousness. Think not?
How many times have you read a book or seen a movie because you heard it was awful? Really awful. Translate and rejoice. You finally get it.
The same thing goes for people who mean you harm by talking about you and creating problems, especially if you're a writer. Their ill intentions usually equal interest and that will equal sales. But don't tell the pot stirrer because they might stop creating problems. You don't want that.
Be a pro. Thank them for the time they took to read and review your book. Ask them to tell all their friends. You might not have to ask; they've probably already spread the word.
Sometimes bad equals good. It's not the best intentions you need, but often evil intentions. It gets more press and generates more interest. Thank the publishing and movie gods for bad intentions.