New York- The monsignor at the center of a steamy sex scandal stood by his woman yesterday – resigning his high-ranking post at St. Patrick’s Cathedral after the church told him to fire his leggy longtime assistant, The Post has learned.

Clark, 79, thumbed his nose at Edward Cardinal Egan’s request Wednesday to relieve Laura DeFilippo, the $100,000-a-year secretary with whom he was videotaped checking into a secluded and romantic Hamptons motel, an insider said.

Sources said the Catholic cleric then abruptly quit after realizing the scandal made it impossible to continue running St. Pat’s, a source familiar with the situation said.

The source said, “He wouldn’t fire her because he claimed he didn’t do anything” with her at the motel in Amagansett, where the two were videotaped July 21 at the behest of DeFilippo’s husband.

In a statement issued by his lawyer, Laura Brevetti, Clark said, “It appears to me that events and circumstances have been portrayed in such a false and sensational manner that I will no longer be able to effectively serve the archdiocese.”

“Consequently, I have submitted my resignation. I thank all the many people who continue to offer me their prayers and consoling messages,” said Clark, who in a 2002 St. Pat’s sermon called the United States “probably the most immoral country in the Western Hemisphere,” referring to its sex-obsessed culture.

Sources said Clark’s decision was made easier by the fact that the high-powered conservative clergyman already was expected to retire from his four-year run at the landmark Manhattan church when he turned 80 in several months.

When asked if Egan had requested Clark to can De Filippo, New York Archdiocese spokesman Joseph Zwilling, said, “I have no knowledge of that.”

In a written statement, Zwilling said, “His Eminence, Edward Cardinal Egan, has today accepted Monsignor Eugene Clark’s resignation from his position of rector of the Cathedral of St. Patrick.”

“Although Monsignor Clark continues to deny the allegations against him, he offered his resignation for the good of St. Patrick’s and the archdiocese. He will not be celebrating Mass or the sacraments publicly until this matter has been resolved,” Zwilling said.

Asked if Egan demanded the resignation, Zwilling said the monsignor – who had been spokesman for one past cardinal, Terence Cooke, and private secretary to another, Francis Spellman – “offered his resignation and the cardinal accepted.”

Clark’s fall from grace followed several days of headlines blaring details of his afternoon sojourn at the motel with DeFilippo, a striking brunette. Both deny they had sex at the motel, but DeFilippo’s husband, Philip, released a videotape showing the couple entering the motel wearing one set of clothes, and leaving almost six hours later wearing different clothes.

Philip DeFilippo – who sued for divorce last week claiming adultery – also has suggested his wife and the monsignor had a long-term affair.

But yesterday, Philip DeFilippo, who turned to the media to air his family’s dirty laundry, hid like a frightened child inside his Eastchester home, peering out occasionally.

The DeFilippos’ 14-year- old daughter – who told police in sworn statements how she saw her mom kissing and sitting on the monsignor’s lap in his hot tub – was dropped off at the home yesterday by women who called reporters “bastards.”

Philip DeFilippo at one point scampered out of his home to his car – after covering his windows and concealing his license plate with wrapping paper. His neighbors used another car to block in the media.

Meanwhile, Catholics were dismayed over the scandal – but grateful the monsignor came to his senses.

“I don’t know how anybody could function in the role of rector of St. Patrick’s knowing that this cloud of suspicion was hanging over his head,” said William Donohue, head of the Catholic League for Religious and Civil Rights. “He would have been functionally disabled if he stayed on.”