She asserted that the development would not affect her relationship with Mrs. Trump, who attended Ms. Winston Wolkoff’s 40th birthday party in 2010 and has traveled in the same circles for years.

“I expect to remain a trusted source for advice and support on an informal basis,” she wrote.

In another email, Ms. Winston Wolkoff said, “I am proud of the work that we did to support the inauguration.”

She said her firm, WIS Media Partners, spent the overwhelming majority of the money it was paid by the inaugural committee on services to subcontractors, including for satellite feeds to be provided to broadcasters worldwide.

The firm “retained a total of $1.62 million for all of its consulting and creative services, which was divided among our staff of 15 members (including myself),” she said in the email. She added that the firm, which had been created only weeks before the inauguration, “submitted all of our records fully audited to the inauguration committee nearly one full year ago in March 2017.”

Ms. Winston Wolkoff said news coverage of her work was “completely unfair,” but she did not specify any errors. In a series of emails, she copied a lawyer from the New York-based law firm Paul, Weiss, Rifkind, Wharton & Garrison and wrote, “There have been a number of unfair and untrue statements about me and I am reserving all rights.”

Ms. Winston Wolkoff made her name planning society galas in New York, including the Costume Institute Gala, also known as the Met Gala, at the Metropolitan Museum of Art. Over the years, she worked closely on the gala with the Vogue editor Anna Wintour. Mr. Monn also worked on the gala, which embodies an exclusive vibe that is in many ways incongruous with the messaging to blue-collar voters that Mr. Trump projected during the 2016 presidential campaign.