Haters can be like bombs. You want to defuse them. Don't shake 'em. Don't drop 'em. Just render them safe. It's possible there's some gold in the ore; there might be, and if there is, accept it gratefully; but it's often hard to tell the constructive true-believer from the vindictive maniac. Your #1 job is to make it all inert, and to be able to walk away without an explosion destroying the business, social-media explosion or otherwise.