"You can now have nothing farther to say," she resentfully answered. "You have insulted me in every possible method. I must beg to return to the house."
Let's take a look at Lady Catherine's insults.
1. She entered the room with an air more than usually ungracious, made no other reply to Elizabeth's salutation, than a slight inclination of the head, and sat down without saying a word. Elizabeth had mentioned her name to her mother on her ladyship's entrance, though no request of introduction had been made.
2. "You have a very small park here," returned Lady Catherine, after a short silence.
3. "This must be a most inconvenient sitting room for the evening in summer: the windows are full west."
4. But, however insincere you may choose to be, you shall not find me so.
5. that you, that Miss Elizabeth Bennet, would in all likelihood be soon afterwards united to my nephew -- my own nephew -- Mr. Darcy. Though I know it must be a scandalous falsehood -- though I would not injure him so much as to suppose the truth of it possible,
6.If! do you then pretend to be ignorant of it? Has it not been industriously circulated by yourselves? Do you not know that such a report is spread abroad?"
7. You may have drawn him in."
8. to be prevented by a young woman of inferior birth, of no importance in the world,
9. You will be censured, slighted, and despised by every one connected with him. Your alliance will be a disgrace; your name will never even be mentioned by any of us."
10. You are a gentleman's daughter. But who was your mother? Who are your uncles and aunts? Do not imagine me ignorant of their condition."
11. I know it all: that the young man's marrying her was a patched-up business, at the expence of your father and uncle. And is such a girl to be my nephew's sister? Is her husband, is the son of his late father's steward, to be his brother? Heaven and earth -- of what are you thinking? Are the shades of Pemberley to be thus polluted?"
12. "I take no leave of you, Miss Bennet. I send no compliments to your mother. You deserve no such attention.
You can respect Elizabeth for keeping her composure during her conversation with Lady Catherine.