Pedro Hernandez’s estranged daughter was shattered to hear that her father confessed to the murder of Etan Patz, her mother-in-law told The Post.

“She’s a mess. She can hardly speak. She didn’t know her father was a killer. She hardly knew him at all,” said the mother-in-law, who would not give her name. Nathalie Hernandez, 27, of Pennsauken, NJ, hasn’t had any contact with her father in years. She is a “wonderful wife and mother,” the woman said yesterday.

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Nathalie and her brother Peter are Hernandez’s children from his first marriage. “She just found out yesterday that her father was a coldblooded killer,” the mother-in-law said.