I have never had (nor heard of) this kind of shenanigans happening as regards LibraryThing reviews (although I can't guarantee it hasn't, it must at least be less widespread - when I searched the LT forums for people mentioning situations like this, the first several results were people talking about stuff that happened to them on Goodreads.) There's a strong user culture there encouraging authors to stay the heck out of their own reviews or criticism of other users' reviews, and a small and responsive staff that focus mostly on user experience rather than selling users' eyes to other people.

Of course that's probably partly because LT is a much less social-oriented site than GR - there isn't actually any way to reply directly to a review, you can only upvote them, and publishers/authors/etc. pay a lot less attention to it.

Also, augh, this sounds like a terrible thing to have happen to you. :/