I fear what may happen if I don't use it, but am more afraid of killing another human being, more afraid of trying to live with the guilt of murdering another person. (Para. 15)
Meaning: I am afraid of what may happen if I don't use the gun, but I am more afraid of killing another human being, more afraid of trying to accept the strong and unhappy feelings caused by the knowledge of killing another person.
n. 罪行,内疚