Jon Gosselin is in the doghouse with Hailey Glassman -- again.

She now says the reality dad, 32, cheated on her with Star tabloid reporter Kate Major. (Glassman previously said Major was "cuckoo.")

She tells she learned Gosselin had a fling with her after being deposed on Monday by TLC's lawyers in the network's breach of contract suit against Gosselin.

"He became a monster," Glassman, 22, told "He's a master manipulator and a compulsive liar."

Added Glassman: "I was told under oath that Jon really did sleep with Kate Major," Glassman told "I'm mind boggled and hurt by it. And he still lies to me about it and denies it to this day."

Glassman said that when Gosselin and Major were photographed together this past summer, everyone told her that Major was "going to pretend to be Jon’s girlfriend so they can take the heat off" Glassman.

"I think back now and say to myself, 'Hailey, you should have been smarter,'" she said.

Although the off-again couple -- who have been together for eight months -- are still living in the same apartment, she wants to move on.

"It's complicated. We're not together," she said. "I just want this to be all over. I want him out of my life."