We like to call this chapter: "Elizabeth Realizes Her Idiocy."
When Elizabeth first reads Darcy's letter, she is still angry, feeling that the letter is no apology for Darcy's behavior.
She is, however, aghast to learn about Wickham. She doesn't want to believe it, so she puts the letter away, saying she will not read it or think about it again.
Still, she can't help herself.
Elizabeth goes for a long, long walk and reads the letter several times over, realizing that, if what Mr. Darcy says is true, it means he is completely blameless in the Wickham affair.
At first, she tries to exculpate Wickham by remembering something he had done that would exonerate his character, but she can't remember anything.
Then she realizes how inappropriate it was for Wickham to have said anything to her about Mr. Darcy at all on their first meeting.
Thinking even harder, she remembers how Wickham waited until the Netherfield contingent had left before he spread his anti-Darcy story wide and far, and she begins to realize that Wickham is guilty of character assassination.
She also realizes that, as odious as Mr. Darcy might be to her, she has never observed anything immoral or unscrupulous in his character.
She is ashamed of herself. Her pride in her own powers of character analysis has blinded her. She has been prejudiced against Darcy.
In light of her new understanding, she re-reads his account of his actions towards Jane and Bingley. Now she can't deny that he was speaking the truth. Jane didn't, after all, wear her heart on her sleeve.
As for his unflattering words about her family, Elizabeth can't help but acknowledge their truth.
When she returns to the house, Elizabeth discovers that Mr. Darcy and Colonel Fitzwilliam had dropped by to say good-bye (they're heading out of town), but they had needed to leave before she returned.