"AMI lied to me, made empty promises, and repeatedly intimidated and manipulated me," McDougal, who was Playboy magazine's 1998 Playmate of the Year, said in a statement today.
"I just want the opportunity to set the record straight and move on with my life, free from this company, its executives, and its lawyers."
Adult film actress Stormy Daniels, whose real name is Stephanie Clifford, sued the President on March 6, stating that Trump never signed an agreement for her to keep her quiet about an "intimate" extramarital relationship between them.
Daniels received US$130,000 under that agreement.
This week, a law firm representing Trump and the corporation that paid Daniels said in a court filing it was seeking at least US$20 million in damages for multiple violations of the non-disclosure agreement.
Today US news organisations reported that Daniels passed a lie detector test on her relationship with Trump.
Also today, a New York state judge says Trump must face a defamation lawsuit by a woman who accused him of sexually harassing her after she appeared on his former reality TV show.
The decision by Justice Jennifer Schecter of the New York state court in Manhattan in favour of California restaurateur Summer Zervos, a former contestant on NBC's The Apprentice, raises the prospect that Trump might have to answer embarrassing questions in court about his behaviour towards women.
She rejected Trump's claim that he was immune from being sued, finding "absolutely no authority" to dismiss litigation related "purely to unofficial conduct" solely because he occupied the White House.
"No one is above the law," the judge wrote.
A White House representative was not immediately available for comment on the ruling.
Mariann Wang, one of Zervos' lawyers, said: "We are grateful for the opportunity to prove that that defendant falsely branded Ms Zervos a phoney for telling the truth about his unwanted sexual groping."
Trump has been accused by several women of misconduct, including after the release during the 2016 presidential campaign of an Access Hollywood recording in which he had spoken in vulgar terms about trying to have sex with women.
He later said the comments were "locker room banter" and his campaign issued an apology from him if anyone was offended.
- Reuters, AAP
