*Spoiler* Q. about his actions

First off, I pretty much liked the movie, it's very well paced and decently played, with a kind of twist that reminded me of the Lynch movie. The ending dotted the i's but there's still one thing troubling me - in real life (not his imagination) before he died he was taking his brother to hospital, right? Then why did he first picture he was actually going to kill him? Was it a wish from the depth of his mind, its dark side? Or does it add to the theory that these moments of reliving were his "own hell" where he had to go through the tormenting circumstances over and over again?