As Nynaeve anticipates, "Egwene would be among the most harsh. To show that she had been right in raising Nynaeve." That is, Nynaeve knows that Egwene would try to cause her pain, and knows why: "to show that she had been right"; that is, to advance her own political career. Whether Nynaeve is right about this (and Egwene did admit that at least the two tests Nynaeve was most revolted by, Emond's Field and Lan, were of her personal devising), I see no reason to believe that she changed her assessment of the situation.

And since, in politics, belief is more important than actuality, that's the key issue. Egwene forced Nynaeve to present herself for torture, both knowing full well why – to stabilize Egwene's personal position – and made no credible apologies for it. That's goes beyond Egwene's usual narcissistic comportment and well into tyranny.