The estranged wife of Sugar Ray Leonard has charged the boxing and entertainment superstar with adultery and physical abuse and humiliation, according to recently unsealed court files of the couple's divorce proceedings in Montgomery County Circuit Court in Rockville.

A court hearing is scheduled Friday before Judge William C. Miller on Juanita Leonard's request to increase monthly payments for alimony and child support from $12,000 to $50,000, celebrity divorce attorney Marvin Mitchelson said yesterday from Los Angeles. Mitchelson was retained several months ago by Juanita Leonard.

Judge Miller ordered the court files unsealed Oct. 22 at Mitchelson's request. The files initially had been closed to the public because of concerns about media publicity and protecting the privacy of the Leonards' children, according to court records.

Ray Leonard and his wife were married Jan. 19, 1980, in a religious ceremony in Prince George's County. The couple have two children, Ray Charles Leonard Jr., 16, and Jerrel G. Leonard, 6.

Sugar Ray Leonard filed for divorce in March of this year. In an amended divorce petition filed in April, attorneys for Juanita Leonard said the couple separated permanently in December 1989. The petition charges that Sugar Ray Leonard "did commit adultery" and says his wife has "neither forgiven nor condoned said acts."

Juanita Leonard's amended petition also alleges that Sugar Ray Leonard "has persistently engaged in cruelty of treatment" and that he assaulted his wife, "causing her bodily injury and has harassed and humiliated her in the presence of her family, friends and others."

Mike Trainer, Sugar Ray Leonard's lawyer and agent, said yesterday that he has filed a motion with Judge Miller to strike Juanita Leonard's allegations of abuse and "unfitness" against her husband. "Nothing that has been alleged has been proven," said Trainer. "Statements like that mislead people in the media."

Miller is scheduled to consider Trainer's motion at Friday's hearing at the same time he considers the increase in payments.

Trainer said he didn't know how much money Juanita Leonard planned to seek in support payments at the upcoming hearing. Although Trainer confirmed the current $12,000-a-month support payment, he said, "You can ask for what you want, but you must bring the receipts with you."

Trainer says the couple share custody of the children.

Mitchelson, who estimates Leonard's wealth "in excess of $50 million," said he plans to take a deposition Thursday from the sports figure at a "private" setting to determine Leonard's total worth. According to one court document filed by Juanita Leonard's attorneys, Sugar Ray Leonard earned more than $30 million in 1989 alone.

Court documents filed by each side state the couple first separated March 9, 1988, but "spent one night under the same roof, without cohabitation, in December 1989." According to court files, "there is no reasonable expectation of a reconciliation."

Juanita Leonard, who owns a clothing boutique at Tysons Corner, currently resides at the couple's home in Bowie, according to Mitchelson and court records. Sugar Ray Leonard, according to court files, stays at the couple's Potomac home, valued at more than $1.5 million. Court records indicate that the boxer owns another home in Largo, as well as stock in several corporations and "a number of luxury cars, other automobiles, and recreational vehicles."

Mitchelson also has asked Miller to invalidate a prenuptial agreement signed Dec. 7, 1979, between the couple. According to Juanita Leonard's amended petition, the prenuptial agreement is "unconscionable" and its terms "completely ignore" her contributions to the marriage. Hearings are scheduled in February on the prenuptial agreement, according to court records.