I disagree slightly, like you said its about a guy who fell deeply in love with a girl who said it would last forever and dumped him later. I think that he loves her so he wants them to try again, she can make it better than before but if she isn't going to he doesn't care about her, hense the chorus. In the line "after today silence will haunt you, expect no forgiveness" he thinks she will be wondering about their broken relationship, thinking she may want to be forgiven for what she did but he has no sympathy or forgiveness for her. There are many references to him killing her but I can also see "as the life fades from your eyes" as a metaphor for their very alive love being dead and her losing her meaning to him. In the line "now i grit my teeth and finish what i know must be done to kill the memory of you" I think it means that he is still in love with her and doesn't want to let her fade away but he has to forget her and move on. That's just what I think its about though :)