A defrocked Catholic priest, branded as a "thief, philanderer and a liar," faces possible perjury and contempt charges after losing a defamation of character suit that he filed against a jilted widow who claimed he was her lover.

Rev. Stanley J. Miaskiewicz, 54, today was ordered by Middlesex Superior Court judge to prove next week that he did not lie during the dramatic nineday trial which jolted the Catholic community here. The case has been referred to the district attorney.

The former priest testified he was "shamed" by charges he violated the priestly vow of celibacy and he claimed he has been spiritually crippled by the detailed romantic tale of a heated cross-country love affair.

Arlene LeTourneau, 59, the affluent suburban businesswoman cleared late Monday of charges she tried to ruin the priest, is now suing Boston's Cardinal Humberto Medeiros for "conspiracy to obstruct justice."

"I was threatened by the church -- a written threat to excommunicate me if I brought the cardinal to testify," she told reporters after the jury of three women and nine men ruled in her favor. The cardinal, she said, knew of the priest's allegedly sordid reputation since 1970.

In a unique court appearance, Cardinal Medeiros testified last week that he suspended the priest last year but that he could not discuss the action because of its ecclesiastic nature. "It is," he said, "a sad affair."

Cardinal Medeiros faces a second suit brought by a man who claims Rev. Miaskiewicz broke up his home by seducing his wife while he was a curate at St. Malachi's Church in suburban Burlington.

Miaskiewicz denied the charges. He decided to sue LeTourneau after she related her story to his superiors -- from the head of his parish, to the cardinal and even to the late Pope Paul VI. The priest and his attorney have characterized the widow as a domineering, vindictive woman determined to destroy the man she loved after he spurned her.

Their romance, she testified, began in March 1974, one month after the death of her husband of 39 years.

For the next 19 months, she said, they lived together "as man and wife" at fashionable resorts and inns like Chateau Montebello in Quebec, Hilton Head, S.C., and Las Vegas. She produced bills, receipts and photographs, noting in a firm voice, "I paid the bills."

Miaskiewicz testified that he traveled alone by bus and would meet LeTourneau in various cities across the country and in Canada. He said they stayed in separate rooms.

"This completely unprincipled woman embarked on a campaign to ruin this priest," said Miaskiewicz's attorney, Gerald N. Cohen. "She did it," he said, "not to rid the Catholic Church of a rotten priest but because she wanted him."