The help is turning on the Kardashian clan ... TMZ has learned a former family nanny is shopping a tell-all book about her time with the K-squad before they were famous  ... and it's clear she HATED some of the kids.

Sources tell us ... the woman behind the book, Pam Behan, served as a nanny, personal assistant and cook for Bruce and Kris Jenner for years ... and spent all sorts of time with the Kardashian girls AND the Jenner boys, Brody and Brandon.