The analyses of a sentence #1

The narrator recalls his childhood.
He and Peggotty, the only maid of his house came to Yarmouth, her hometown and visited her brother, Mr. Peggotty's house.
They stayed there several days.
They just now came back home, and he knew his mother was remarried, and that his bedroom was removed to another place; he cried himself to sleep in his old bedroom.

"Davy," said my mother, "Davy, my child!"
I dare say no words she could have uttered would have affected me so much, then, as her calling me her child. I hid my tears in the bedclothes, and pressed her from me with my hand, when she would have raised me up.
"This is your doing, Peggotty, you cruel thing!" said my mother. "I have no doubt at all about it. How can you reconcile it to your conscience. I wonder, to prejudice my own boy against me, or against anybody who is dear to me? What do you mean by it, Peggotty?"
Poor Peggotty lifted up her hands and eyes, and only answered, in a sort of paraphrase of the grace I usually repeated after dinner, "Lord forgive you, Mrs. Copperfied, and for what you have said this minute, may you never be truly sorry!"
[David Copperfield by Charles Dickens]
I'd like to know why it is "you"s, not "she"s in the prayer.
Thank you in advance for your help.