In chapters 18-22 of The Catcher in the Rye, Holden's plummets toward self-destruction, but he wisely chooses not to suicide like James Castle. In these pivotal chapters, the book seems destined toward tragedy, but Holden's conversations with Antolini and his sister move the resolution (though open-ended) back toward comedy.
Holden is a sadist. He baits Carl Luce to beat him up just like he got Stradlater and Maurice to punch him. Holden wants someone to punish him for some unresolved guilt (possible survivor's guilt over his brother's death). Luckily, Luce leaves.
Then, Holden goes to Mr. Antolini's, who, as a counter-culture spokesman, seems set up to be the Deus ex Machina (savior) of the novel. He gives Holden great advice, and his voice seems to be that of the author's: he says Holden is “in for a terrible fall.”
The mark of the immature man is that he wants to die nobly for a cause, while the mark of the mature man is that he wants to live humbly for one.
Remember, Antolini was the one who found and carried James Castle's body to protect him from the rubber-necks. This is want Holden wants: to commit suicide, and he's going to Antolini's to see how it will play out.
You see, James Castle (J. C. --“Jesus Christ”) is Holden’s martyred saint. Castle fell to his death rather than take back any of the words he said about others (He called them "conceited"). Similarly, Holden doesn't want to take back calling people "phonies." He wants to die young, a misunderstood romantic hero like Mercutio (from Romeo and Juliet), another non-phony.
After this, Salinger discredits Antolini by having him make a pass at the boy. So, the episode is ironic, weird, and ultimately anti-climatic. Holden continues his episodic journey toward being a catcher in the rye.
Holden knows his role as a catcher is doomed to fail. He can't even protect Phoebe from the evils of the world (the f-bomb). Holden finally realizes that he must enter the adult world. So, he goes home to get mental health treatment.