I think in your comments at the end you grasped a key aspect of Jimmyβs character: he often tells the truth by lying, and he lies by telling the truth. This ending scene was one of the clearest examples, but there are many others. Jimmy is overcome with real emotions, all the things heβs saying are true, but he only feels safe releasing them in the context of a con. I think Jimmy really struggles to process negative emotions, and he seems to need all these layers of irony and performance and deception as a kind of armor before he can admit what heβs really feeling.