I think that true statements could be considered disparaging. Consider something like:

"Zelphirkalt claims they do not abuse their child. Despite this their kid has been seen at the ER for broken bones multiple times in the last 10 years, and spent a few months in therapy."

Even if I know that your kid's ER visits were for:

1) a broken leg from a fall out of a tree

2) a broken finger from their martial arts lessons

3) a broken nose from defending themselves in a fight

and that the therapy was mandated by the school system as a result of the fight and a "zero tolerance" policy, the text of the statements in question are still absolute truth. I've just phrased it in such a way (and declined to report on other truths) that a reader is encouraged to draw the conclusion that you abuse your kid physically and emotionally. I think if I published something like that in a book, you'd certainly consider it disparaging, and I think a court might agree if you were enforcing a non-disparagement contract I had signed with you.

That said (at least in the US) I doubt a court would find it to be "libel" or "slander", since those are MUCH higher bars to clear by default and assuming you were a famous individual (or company like facebook) the bar is even higher. Something like this would likely hinge on my own reputation and how likely a reader is to assume I'm speaking from "hidden knowledge" as opposed to coming to a given conclusion from public knowledge.