Was he already crazy to begin with, and Flavia just gave him a gentle push over the edge? From the very beginning, he seemed to display some erratic and paranoid behavior, and she simply took advantage of this fragility and used it to her own ends.
shareYes, I'd say that he was mentally unstable from the beginning. This is evidenced by the s/m nightmare in the opening scene, and the subsequent scene where he sees himself in close physical proximity, i.e. the nurse pushing Leonardo in a wheelchair past Leonardo.
I'm watching/recording it on TCM right now (as part of their Halloween movies). So far, it's been nothing but 40 mins of illogical disjointed scenes. Yeah, he's definitely insane.