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"When Superman says "Save Martha" and "You're letting Martha die" or something to that effect, Batman is instantly snapped back to the loss that he could never cope with, the real nightmare that has haunted him all his life and that has pushed him further and further away from the feminine. He gave his life up to battle crime, it was his coping mechanism but in the end he realised it was all for nothing. Neither could he stop crime and make Gotham a better place nor could he ever change what had happened with his parents even though he tried to fix it with his actions for 20 years by taking up the mantle of the Bat, which was the "beautiful lie" he references at the beginning of the film.
All the losses he faced during his life - the death of his parents, the death of Jason Todd (Robin), seen by the Robin suit with the Joker's scribbled taunts, in the Batcave, the loss of his Wayne Financial employees in the battle between Superman and Zod - all lead him further and further away from the feminine. When Luthor manipulates Bruce and strikes the final blow with the note that says "You let your family die" it invokes the darkest parts of the masculine in Bruce since it reminds him of all the times that he was powerless to save his various families, and takes over him completely leading to his absolute and unwavering resolve in killing Superman.
(An interesting point to note, noticed by someone online: Bruce's dreams all start and end with the sound of the World Engine destroying Metropolis in the Zod battle, signifying that the losses faced by Bruce at that point subconsciously reminded him of his losses as a child since he was powerless to do anything in both instances. He therefore equated his parents' killer to Superman and the Kryptonians and started seeing himself as the potential saviour of humanity.)
By becoming blind with rage and almost killing Superman, he truly was "letting Martha die" since he had suppressed his losses and the feminine, the good, and became the very thing he fought against all his life - the overpowering and uncontrollable masculine. But hearing his mother's name reminded him of why he started fighting crime in the first place (to do good) and that brought him back from the edge."
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you can read it here... if you care... and want to know why it works
http://forums.superherohype.com/showthread.php?t=512399