Ms. Manigault Newman - who first gained fame as a contestant on Trump's reality show "The Apprentice", and then secured a $180,000-a-year staff job at the White House - released a recording of a private conversation she had with the president after she was sacked.
Omarosa said that she had not heard the alleged recording of the president using the slur while she was working in the White House.
"When you give a crazed, crying lowlife a break, and give her a job at the White House, I guess it just didn't work out", Trump tweeted. "This is somebody I've known since 2003", Manigault Newman said.
In tweets Monday night, Trump denied ever using "such a awful and disgusting word", and his aides have denied having strategized about how to contain the damage if such a tape surfaced.
After leaving the White House, Manigault Newman was "downhearted" because Trump "ceased all correspondences with her", an unnamed "insider" source told The Daily Mail.
She declined to say how many more tapes she'll make public. So should Trump's tweetstorm against his former ally, says Daniel Urman, a law and politics expert at Northeastern University.
"It sounded as if [Trump] used [the N-word] everyday", Manigault-Newman said on MSNBC's "Hardball with Chris Matthews" on Monday night.
"Absolutely. Particularly with African-Americans, he thinks we're all stupid", Newman said.
England vs India 2018: Ravindra Jadeja Vouches for Visitors to Return Stronger
On the other hand, England is on a roll, with Anderson and Broad - combined age of 68 - bowling as well as they have ever done. As India slumped to a humiliating defeat in the Lord's Test, Virat Kohli walked out with a blank expression on his face.
To that end, Omarosa attempted to contact me just two days ago, but I refused to accept her call.
After growing up in a housing project in Youngstown, Ohio, and losing her father at age 7 - he was murdered - Manigault Newman emerged from a turbulent youth to earn a degree in broadcast journalism at Central State University and land a job in the office of then vice president Al Gore at age 23.
He added: "While I know it's "not presidential" to take on a lowlife like Omarosa, and while I would rather not be doing so, this is a modern day form of communication and I know the Fake News Media will be working overtime to make even Wacky Omarosa look legitimate as possible". "Omarosa had Zero credibility with the Media (they didn't want interviews) when she worked in the White House".
The source claimed: "Melania is exhausted of being quiet and hiding inside the White House".
When asked to clarify on NBC's "Meet the Press", Manigault Newman said she listened to the recording after finishing the book during a trip to Los Angeles.
The tape recording appears to show Trump expressing surprise about her firing, saying "nobody even told me about it".
"I would rarely see her but heard really bad things", he added.
The White House claims the book is "riddled with lies". "I wonder if she is recording some of the things that we've talked about as well", he told Fox News' "Fox & Friends".
She says Mr Trump offered her £12,000 a month to serve in a "senior position" on his 2020 re-election campaign, but only if she signed a non-disclosure agreement.