From Britney’s breakdown to Jamie Lynn’s teen pregnancy, Lynne Spears has weathered a multitude of parental problems. Now, in an explosive tell-all book, Lynne Spears: Through the Storm, due out on September 16, In Touch can exclusively reveal that the 53-year-old defends herself against criticism that she’s failed as a mother.

By February 2007, her world had crumbled. Britney, in the midst of a mental breakdown, shaved her head. “It’s a mother’s worst nightmare,” the source says.

Last fall, Lynne was hit with another shocker — Jamie Lynn, 17, was pregnant by boyfriend Casey Aldridge. Perhaps most disturbing is the way that Lynne found out she was going to be a grandmother again. “Lynne writes that they handed her a note,” reveals the source. “She was furious.”

Since the arrival of Jamie Lynn’s daughter, Maddie, in June, Lynne’s rage has subsided. But according to the insider, there is one person whom Lynne will never be able to forgive for destroying her family — Britney’s former friend and manager Sam Lutfi: “She makes Sam out to be a monster and a predator who took advantage of Britney when she was most vulnerable.”

After reading the book, “You really feel for Lynne,” the source adds. “All she ever wanted was to raise a happy and healthy, loving family.”

For more check out the new In Touch, on sale now.