I've always felt like this song was talking about a person who got horribly hurt by someone, either mentally or physically, and only when they stepped back and really thought about everything did they see it. This, understandably, angered them a lot, especially once they saw the scars and pain left by the one who hurt them, and they're done just standing there and taking it. They have no sympathy for the person who hurt them, and too much damage has been done for apologies to mean anything, and now they're going to go give the person what they feel is coming to them, possibly murder, and grin while doing it.
I've always felt like this song was talking about a person who got horribly hurt by someone, either mentally or physically, and only when they stepped back and really thought about everything did they see it. This, understandably, angered them a lot, especially once they saw the scars and pain left by the one who hurt them, and they're done just standing there and taking it. They have no sympathy for the person who hurt them, and too much damage has been done for apologies to mean anything, and now they're going to go give the person what they feel is coming to them, possibly murder, and grin while doing it.