Steamy Romance Turns Frosty in Boston : Relationships: Foothill High grad Catherine de Castelbajac and multimillionaire Bill Koch play out their breakup in the courtroom. The reports of torrid notes, extravagant spending and connections to European demi-royalty captivate the normally staid city.

Talk about a Puritan image problem. First Demi Moore does Hester Prynne. Then Catherine de Castelbajac--a former Ford model and Californian who graduated from Foothill High School in Santa Ana--portrays herself in a courtroom as an “X-rated Protestant princess.”

“My poor nerve endings are already hungry,” De Castelbajac told Bill Koch--a multimillionaire yachtsman who gained fame for his 1992 America’s Cup victory--in one of a series of steamy letters and faxes read to jurors. “You are creating such a wanton woman.”

The correspondence became public during a sensational trial that has made screamer headlines and ended last week with a jury voting to boot her out of a pricey Koch Boston condo. Koch had sought to evict De Castelbajac from his $2.5-million condominium at the Four Seasons Hotel. She now has 30 days to clear out or, if she appeals the decision, to begin posting $15,000 a month rent.

The daily reports of torrid communiques, extravagant spending sprees and connections to European demi-royalty captivated a community where “staid” and “sedate” remain the ruling complimentary adjectives of choice. How one woman could be expected to drop $7,500 on a single frock mystifies a steadfastly thrifty populace.

Koch, 55, did not contest the fact that he gave that amount to De Castelbajac, 43, to purchase a dress. In court she conceded that she instead spent the money on “an operation.”

“What kind of operation?” asked Koch’s attorney, Elizabeth A. Burnett.

“A cosmetic operation,” De Castelbajac replied.

Liposuction, to be precise. (Where on her body the liposuction occurred was not revealed.)

Known to intimates as Kate, Catherine Chambers was born in Santa Barbara and in 1970 graduated from Santa Ana’s Foothill High, where she was voted by her fellow seniors the female student who had “Done the Most for the School.” A popular Associated Student Body Cabinet member, she was hip enough to throw a peace sign in a yearbook photo, her long streaky blond hair falling across her cover-girl face.

She went on to New York City’s Barnard College. Her selection in 1975 as Mademoiselle magazine’s college model of the year launched her on an international career.

In Paris she became acquainted with Jean Charles de Castelbajac, a marquis-turned-fashion designer whom she married in 1979. One of their two sons has been living with his mother in Koch’s 3,700-square-foot apartment opposite Boston’s Public Garden. Under terms of her divorce from the marquis, Catherine de Castelbajac received a $30,000 cash settlement, an art collection she estimates to be worth $400,000 and yearly payments of $80,000 until the year 2004.

A recent Fortune magazine report placed Koch’s net worth at $600 million. He is a native of Kansas with three degrees from the Massachusetts Institute of Technology and an assortment of businesses in New England, Florida, Kansas and Colorado. Koch said in court that he thinks of himself as a sportsman and “a philanthropist of sorts.”

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They met in 1992 when friends of his invited her to his Cape Cod estate. While their love was fresh, Koch described De Castelbajac as “a woman that all men dream about.” But in an interview with the Boston Herald--trumpeted on the front page, as was a week’s worth high-profile coverage of the proceedings--Koch said he had investigated De Castelbajac and found her to be little more than “a Santa Barbara surfing girl.”

But love is legendary for its blind spots. During their 2 1/2-year liaison, De Castelbajac sent faxes to “Big Beautiful Bill.” She faxed rhapsodic about “those arms, those shoulders, . . . those kisses!” In a paean to techno-romance, she characterized her passion for Koch as “beyond calculation by the largest computers.”

In court, though, it was hard to imagine such ardor. Frumped up in an austere navy blue suit and gumdrop-sized pearls, De Castelbajac wore horn-rimmed glasses and sat with her chin in her hands. Her blond hair was swept into a stylish chignon that even Hester Prynne might have admired. Koch, for his part, wore owlish eyeglasses, the kind of Mod hairstyle popularized by the Beatles in the late 1960s, jowls and a scowl.

Jowls or no jowls, De Castelbajac maintains she “gave up a whole life in Europe” to live with Koch in Boston. She said that after she settled into Koch’s life, his friends “consistently remarked how you had changed--and how happy they were to see that you could be with a woman who wasn’t a bimbo, or a prostitute or a psychotic.”

De Castelbajac at first moved into her own apartment in the chic Back Bay section of Boston. Koch asserts that in May 1994, she asked to relocate to his seldom-used apartment at the Four Seasons. Even though he had married Joan Cranlund of New York, the mother of his 9-year-old son, a month earlier, Koch consented.

Koch claims he tried repeatedly to end their relationship. In a letter from November 1994, he told De Castelbajac that he was unwilling to make a commitment and admonished: “Perhaps I am not the man for you.”

As their affection waned, De Castelbajac wrote, “I still don’t believe that this is my Billy. Something must be very, very wrong in your life now.”

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Koch alleges that from October 1994, to August 1995, De Castelbajac ran up $47,000 in charges at the Four Seasons. Among the itemized expenditures was $2,500 for cat food.

Koch also asserted that De Castelbajac had offered to resolve their squabble for a payment of $5 million. Through his newly hired public relations handler, Koch retorted that “I’ll pay 10 times in legal fees whatever I pay her.” Sure, he agreed, spreading the squalid details of his love life all over the fluorescent-lit hearing room at the Boston Housing Court was less than enjoyable. “But I don’t believe in false promises or idle threats.”

Besides, Koch reminded De Castelbajac in a July 23 epistle that became part of the court record, “You did not come to Boston to live as man and wife with me. You came, as you told me, to get an MBA from Simmons College.”

In her fourth day of testimony,De Castelbajac explained why she had no written evidence of Koch’s commitment.

“It was precisely not a business deal,” she said. “In love relationships, commitments and promises you make are not written down.”

Also contributing to this report was Times staff writer Nancy Wride in Orange County.