Hefner, 85, and the former Playmate were set to walk down the aisle Saturday at the magazine mogul's mansion, but sources say the two canceled the plans following a heated disagreement.
"There are two mistakes one can make along the road to truth ... not going all the way, and not starting," Harris tweeted to her fans early Tuesday, the same day she launched her music career with the release of her single "Club Queen."
Hefner had proposed to the buxom blonde on Christmas Eve with a sizable diamond sparkler.