Kate Major: Jon “Needs to Man Up, Tell the Truth”

Hours after Kate Gosselin tearfully said she was "shocked" Jon had begun dating so soon after their split, another Kate had harsh words for the father of eight. In an exclusive interview airing Monday evening on E! News, former Star tabloid reporter Kate Major called the 32-year-old reality show dad a "liar" for denying they had a romantic relationship. (Gosselin's originally slated interview on E! has been canceled, a spokesperson said earlier.) "We had plans to travel together, to live together, and to be together," Major, who dined with Gosselin in NYC and in the Hamptons throughout July, said. "He made his decision in the Hamptons. He wanted to be with me."

Get to know Kate Major and Jon's other women.

Last week, however, Gosselin reportedly said his relationship with Major was strictly platonic. He event told Usmagazine.com that he was still with his 22-year-old girlfriend. ("My heart is always with Hailey [Glassman]," he told Us.) But according to Major, Gosselin told her he was going to break up with girlfriend Glassman in order to be with her. As a result, the 26-year-old resigned from her job, citing a "conflict of interest." "I was with the person I was reporting on," Major said. "He's the one who actually told me to quit my job… He told me he was going to Massachusetts to break up with [Glassman]. I know the truth. He knows the truth. Unfortunately, she did not."

See photos of Jon and Haily Glassman in France.

She even said that the newly single star attempted to date them both. "He tried to two-time both of us," she said. "He wasn't honest with Hailey. He needs to man up and tell the truth. I'm not going to be the other woman." She added: "In no way did he tell me he was going to go parade with his ex-girlfriend." Because Gosselin has denied they ever dated, Major said the resulting claims that she lied to get media attention have been hard to handle.

Look back at photos of Jon and Kate Gosselin through the years.

"It's been a nightmare. I did not want to have to do this," she said. "I did not want to have to sell him out, but when he makes me look like a liar, a fool, and an idiot. I have to speak out." Major also told E! News that she has proof they had a romantic relationship. "I was not the only one who was around when we were romantically involved," she said. "We were holed up together. It's not like we were just sitting there doing an interview." For the full interview with Major, tune in to the special hour-long edition of E! News Monday at 7 p.m. EST.

Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!

Want stories like these delivered straight to your phone? Download the Us Weekly iPhone app now!