This article is important: Why the Trolls Will Always Win
The take away is the very important point that “ignore the trolls” is the worst advice you can possibly follow. It’s like ignoring bullies in school: they simply take it as evidence that they can abuse you without repercusions, so they escalate their attacks.
Personally, I’m in favor of fighting back against the trolls in real life. Invesitgate, find them, hunt them down, file lawsuits for slander, do everything possible to make them pay for their crimes.