What's your analysis?

We know he already didn't like her; she was his nemesis and she caught him. Because of her Spector lost the fake normal life he enjoyed. He could no longer see the one person I think he really loved, his daughter Olivia. So he had this baseline dislike of Stella for these and other reasons.

But in the interview room Stella provoked him. She had made no secret that she detested him, and her personal feelings were on display in the interview. I thought she went a bit beyond what was needed to get him talking as she pushed him, perhaps even taunted him. She correctly described Spector as a performer, and she ripped away the facade he was using to manipulate those around him even then as she confronted him. Spector could feel a sense of control over things as long as he could fool people, manipulate them to his own advantage. Spector could also pride himself on being smarter, superior to those who bought his performances. He was still at that moment successfully presenting the signs of amnesia, and had been able to gain the sympathy of his nurse. Stella showed him it wasn't fooling her. She repeatedly challenged him, accusing him of malingering, faking his amnesia, and telling him to stop. Also, her contempt for him must have been evident to Spector as well.
There she was, that successful, professional, English woman who had ferreted him out, robbed him of his family and his freedom, and was now robbing him of his control and his sense of superiority. Stella tore away the mask, the fiction Spector had created which he himself believed, that he was a superior being able to manipulate others for his own purposes because he was smarter. Stella took that away too. And he snapped.

Spector had consciously adopted a philosophy (if you can call it that) that he had the right to punish others for his own misery and misfortunes. That motivated his torture-killings. He admitted he was unable to overcome the need to do these revenge killings, even though they threatened the normal family life he enjoyed. It was like an addiction, but one he didn't want to beat. He dealt with his frustrations and his anger by hurting women who he felt had better lives than he'd had. He resented successful women. He enjoyed inflicting pain and terror on them. Stella Gibson was a successful woman. When she revealed him, made him face himself and his sickness, he snapped.

How would you describe or explain his violence toward Stella?