Kate Gosselin is allegedly freaking out over what her estranged son Collin will reveal in his upcoming memoir, “In the Shadow of Eight: Surviving the Reality of My Childhood.”

“Kate had no idea this book was in the works,” an insider told the Daily Mail on Saturday, noting that the TLC alum, 51, hasn’t spoken to Collin since she institutionalized him as a child.

“She didn’t expect any of this to ever come out. Now she’s spiraling because she knows it’s about to hit the fan,” they continued.

Kate, who shares the 22-year-old with ex-husband Jon Gosselin, has allegedly told people that her son’s accusations are based off of “zero facts.”

However, Collin claims he has “the evidence to back everything up.”

“Kate can’t stop this book from coming out but I have no doubt she wishes she could,” the source insisted.

According to the source, Collin’s sextuplet siblings, Aaden, Joel, Alexis, Hannah and Leah, and twin siblings, Cara and Madelyn, 25, will also be blindsided by his tell-all.

The insider claims the brood doesn’t “really know the truth of what happened to him” beyond what Kate has said.

Page Six reached out to a rep for Kate for comment.

The cover of the book, which was revealed Tuesday, features an old photograph of Kate covering Collin’s mouth with her hand.

Collin promised to expose “the shocking facade of his picture-perfect family” in the tell-all, which releases this fall.

According to the publisher, fans will hear the “never-before-told story of how [Collin] escaped and found his way back from the dark.”

“This is a reckoning with the dark side of fame: the systems, the entourage, and the institutions that allowed one boy to be erased,” the statement added.

In his book, Collin will touch on “being held down, the basement cell where he was hidden for years and the cocktail of powerful antipsychotics forced on an 11-year-old boy.”

The former reality star is also recounting a “Christmas morning where the gifts were reclaimed as soon as the cameras went down.”

Jon, 49, and Kate were married from 1999 to 2009.

In 2007, the family rose to fame on the TLC reality show “Jon & Kate Plus 8.” After Kate and Jon’s split, the show was renamed “Kate Plus 8” and aired until 2017.

In 2018, Jon was granted sole custody of Collin.

Since moving in with his dad, Collin has continued to speak out against his mom, claiming he suffered “child abuse and child exploitation” at the hands of the “Dancing with the Stars” alum.

Collin alleged he was zip-tied and locked in a basement and even institutionalized against his will.

However, Kate has denied her son’s abuse claims.

While Hannah ended up also moving in with her dad and brother, Madelyn has defended her mom.

In 2023, she accused Collin of “physical violence” and “hate speech” — both of which the author and Jon have denied.