(nypost) Kris Jenner, mother and business brains of the Kardashian klan, is finally telling what she knows about the O.J. Simpson murders.

In a memoir set to hit bookstores tomorrow, Jenner says Simpson’s ex-wife Nicole told her she lived in fear that “he’s going to kill me and he’s going to get away with it.

“She was a wreck,” Kris writes. “She was convinced that someone was looking in her windows and climbing through her bushes in the middle of the night.”

Nicole even called on the day of her murder in June 1994 to ask for help, according to Jenner.

“Nicole said, ‘Can you get over here . . . ? I need to talk to you,’ ” Jenner writes in the book, “Kris Jenner . . . and All Things Kardashian.”

“It’s really important.”

Jenner, who had divorced lawyer-husband Robert Kardashian three years earlier and was married to Olympic athlete Bruce Jenner by then, said she was tied up.

“‘That’s okay, [but] can you meet me tomorrow for lunch?’ ” the book quotes Nicole as saying. “I really have to talk to you about something really, really important.’

“It would be the last time I would ever speak to Nicole,” Jenner writes.

The next morning, news broke that Nicole and a casual friend, Ron Goldman, had been found stabbed to death.

“I instinctively knew that in some way O.J. had something to do with her death.

“I truly couldn’t believe she had been so betrayed by the person who she had once loved most. That O.J. would be so destructive and selfish and jealous. That he would do that to her was just mind-blowing to me. All these thoughts were running through my mind: This can’t be true.”

It was only then that Kris says she learned, through a mutual friend, that “Nicole had been beaten up by O.J. and she had been keeping this physical proof in the form of photographs and, it would turn out, other evidence, in which she had documented 17 years of abuse.

“Nicole really wanted someone close to her to know what was going on, so that somebody — namely me — could be a witness.”

Jenner says she has lived with guilt ever since.

“I had let her down,” she writes.

Jenner apparently felt that she could finally reveal her dealings with Nicole after her ex-husband died in 2003 and O.J. was serving a 33-year sentence in Nevada for engineering the strong-arm theft of his own sports memorabilia.