This quote seems to be what the book pivots on. Justin has transformed himself from an abused farm boy to a rock star by creating his Judas Coin persona. It's a persona he has adopted for so long that it has become the self he recognises when he looks in the mirror, the one he thinks he will offend if he does something that rubs against the grain because it's inconsistent with who he is. We are told that Judas/Justin believes that:
"His own identify was his first and single most forceful creation. The machine that had manufactured all his other successes. Which had produced everything in his life that was worth having and that he cared about He would protect that to the end."
This may be Justin's central problem. He wants to protect Judas. Yet Judas was the one who betrayed with a kiss. The one who placed pragmatism and survival ahead of love and hope. The one who ultimately couldn't live with himself. It was as Judas that Justin has been so careless with his own life and the lives of those close to him that he is now surrounded by nothing but wreckage.
It think that if Justin want's to avoid the silver razor on the gold chain, wants to erase the dark scribbled across his eyes, he may have to throw Judas under the bus.