The main character keeps being told that his problem is he keeps it all in. He retorts that keeping it all in is a virtue. It's better to bottle things up in an angry conversation than actually stab your partner. It's wise to keep quiet about your murders and robberies. It's heroic to refuse to break when you're tied to a chair to be tortured and interrogated. The irony is that for this angry hateful murderer/robber, keeping it all in is not "his problem", it's the least of his problems, and arguably a good thing in his case.
The main character keeps being told that his problem is he keeps it all in. He retorts that keeping it all in is a virtue. It's better to bottle things up in an angry conversation than actually stab your partner. It's wise to keep quiet about your murders and robberies. It's heroic to refuse to break when you're tied to a chair to be tortured and interrogated. The irony is that for this angry hateful murderer/robber, keeping it all in is not "his problem", it's the least of his problems, and arguably a good thing in his case.