Thoroughly enjoyable, though thoroughly unbelievable (spoilers)

Saw this tonight, liked the twisty flashbacks but in the end thought it was pretty unbelievable. It was too convenient that he happened to fire his receptionist, and that the young doctor worded his attack, using the word 'career' to make him think he was referring to the fired receptionist, thereby dismissing him as her boyfriend, letting the real villain go undetected. Also convenient the doctor happened to be seeing another patient who was a bit touchy feely, causing him to think she was the psycho, letting the real villain go undetected again.