She was a managing director of philanthropic consulting firm Changing Our World and a founding board member of the Twin Towers Fund.

[4] The Nathans' marriage fell apart during the early 1990s and led to a contested divorce case and custody battle, which included accusations of abuse from both parties.

[4] Now a single mother, she worked part-time in a dentist's office[1][4] and attended New York University computer and business classes at night and on weekends.

[23] Around this time Judith became romantically involved with Woodhull Hospital clinical psychologist Manos Zacharioudakis;[24] she and her daughter lived with him for four years, until early 1999.

[8] Judith Nathan met Mayor Giuliani in May 1999 at Club Macanudo, an Upper East Side cigar bar;[22] they have said they were introduced by a doctor who is a mutual friend.

[25] Nathan aggressively researched treatment options and Giuliani was quoted as saying, "I felt so fortunate to have not only someone who loved me and cared about me, but also someone who was an expert with an enormous amount of knowledge of medicine and science — she was the single biggest support that I had.

[35] Her first marriage to Jeffrey Ross was revealed in the press for the first time,[14] her educational background was clarified,[14] and she appeared in a Barbara Walters interview on 20/20.

[37] An attempt by the campaign over summer 2007 to rehabilitate her image fell victim to internal tensions,[35] and instead her public appearances were scaled back.

On August 2, 2022, it was announced that Judith Giuliani had hired attorney Dror Bikel and filed a lawsuit against former husband for non-compliance regarding the divorce settlement.

[38] In March 2001, desiring less travel and reduced public visibility, Nathan left Bristol-Myers and became a fund-raiser and later the managing director of Changing Our World,[10] an international fundraising and philanthropic services company headquartered in New York that helps not-for-profit groups raise money for causes such as juvenile blindness and HIV/AIDS in Africa.

[8] After the September 11 attacks, Giuliani credited Nathan with coordinating the efforts of the Family Assistance Center at Pier 94, a claim disputed by the first director of New York City's Office of Emergency Management, Jerry Hauer,[4] but supported by others who say she played a valuable role there that lasted for four months.

[1] Rudy Giuliani wrote of this period in his 2002 book, Leadership, explaining that she capably served as a solid mayoral adviser after September 11 because she "had been a nurse for many years, and afterward a pharmaceutical executive; she had managed a team of people and had many organizational skills.

[4] She became a founding board member of the Twin Towers Fund, appointed by Giuliani,[4] which raised and distributed $216 million to over 1,150 families and individuals.

[40] Additionally, Judith Giuliani has raised funds for Southampton Hospital,[41] Finding a Cure for Epilepsy and Seizures (FACES), Christian Blind Mission International (CBMI), Hurricane Katrina relief in New Orleans,[23] St. Vincent's Hospital Level 1 Trauma Unit,[23][42] Cabrini High School and Cabrini Medical Center,[5][23] and the McCarton School for autistic children.