When Valeris was getting grilled on the bridge, but before Spock forced himself upon her, my heart was already going out to her. I don't know ... she was sympathetic, even after she was left to contemplate her sins. That moment, for me, was when Valeris reminded Kirk, ".. let them (the Klingons) die, you said. Did I misinterpret you?" Because, you know what? Kirk did say that and at the time, the way it's edited together, he did mean that. And I know that Shatner asked for a gesture to be allowed after saying that, to sort dismiss it, like he did not, in fact, mean it. But we don't get to see that.
What we see is Captain Kirk ready let the Klingon empire collapse. And Valeris can't help but be further misled by this. Someone of Kirk's stature in Starfleet and his place in Galactic History is voicing the same, exact rhetoric that the very conspirators she was recruited by are spouting. It could've only cemented her reasoning for doing what she felt she had to do. "Did I misinterpret you?" and no fuss is made over the line. She's not even shown saying it. But it so defines her, in that moment ...