by Breaking Celebrity News Staff

In the wake of her shocking decision to call off this weekend's wedding to Playboy magnate Hugh Hefner, Crystal Harris gave her side of things on Ryan Seacrest's KIIS-FM radio show Wednesday.

Hefner, 85, and Harris, 24, were slated to wed June 18, but according to a source of ours, "Crystal bailed and left the mansion at 11 pm Sunday night."

So ... what happened?

"I called it off because I didn't think it was the right thing for me to do," Harris told Seacrest, adding the the decision "was mutual between Hef and I.

"There was no fight, we sat down and we talked about it."

AUDIO: Harris Breaks Silence On Wedding Shocker

While a source told Breaking Celebrity News Harris is dating Dr. Phil's son Jordan McGraw, she said "she's not seeing someone else."

Harris said she'd had ice cold feet leading up to the big day.

"For a while, I've been having second thoughts about everything,” she admitted. “I haven't really been at peace with myself lately. I didn't think it was really fair to him ... it was all happening too fast for me ... I just thought about it and asked myself, 'Was this what I wanted?'"