...In his biting letter, Trump wrote that Stewart's version of "The Apprentice" was "a mistake for everybody — especially NBC."

The real-estate mogul was responding to Stewart's sniping to Newsweek that "Martha Stewart: The Apprentice" floundered last fall — canceled after one cycle — because Trump would not take his competing show off the schedule.

Her show was supposed to be the only "Apprentice" and was meant to start out with her firing Trump on the air, she told Newsweek, reiterating comments she'd made before.

"Having two `Apprentices' was as unfair to him as it was unfair to me," she told Newsweek. "But Donald really wanted to stay on."

Trump's blunt response asks Stewart to take responsibility for her "failed show."

"Your performance was terrible in that the show lacked mood, temperament and just about everything a show needs for success," he wrote. "I knew it would fail as soon as I first saw it — and your low ratings bore me out."

Ouch.

"Between your daughter, with her one-word statements, your letter writing and, most importantly, your totally unconvincing demeanor, it never had a chance — much as your daytime show is not exactly setting records," he wrote.

Then he really told her what he thought.

"Essentially, you made this firing up just as you made up your sell order of ImClone," said Trump, who claimed NBC did not intend to fire him on Stewart's show.

In a statement issued late Tuesday, Stewart, who lost an appeal last month that ended her criminal case for lying about a stock sale that sent her to jail for five months and nearly six months of house arrest, said she was bewildered by Trump's comments and tone.

"The letter is so mean-spirited and reckless that I almost can't believe my longtime friend Donald Trump wrote it," she stated. more