Theodor Adorno, defined Schadenfreude as "largely unanticipated delight in the suffering of another which is cognized as trivial and/or appropriate."
Nietzsche comments that
Schadenfreude originates in the fact that, in certain respects of which he is well aware, everyone feels unwell - is oppressed by care or envy or sorrow: the harm that befalls another man makes him our equal; it appeases our envy. If, on the other hand, he happens to feel perfectly well, he nonetheless gathers up his neighbour's misfortune in his consciousness as a capital upon which to draw when he himself faces misfortune: thus he too experiences schadenfreude.
Human all too Human 27.
As an aside, in the throes of paranoid insanity some ten years ago, the description of a culture defined by extreme Schadenfreude, really helped me have the strength to wonder if it mattered how cruel people seemed to be.
So leading on from that, might that apparent equivalence between Nietzschean and critical theory, be a useful stepping stone to saving Nietzsche?