Erica Jong's new book was written, the author says, as a "valentine" for her 5-year-old daughter, Molly. Originally titled Molly's Book of Divorce, the 64-page illustrated children's story is a bittersweet and humorous depiction of divorce as seen through the eyes of its 4-year-old title character. "It's a healing, sweet, lovely book to help a child understand divorce," says Jong. "It's a gift of love from me to Molly."

Unfortunately for Molly, the book has only sparked more animosity between her divorced parents. In January Jonathan Fast, Molly's father and Erica Jong's ex-husband, wrote to New American Library, the publisher, objecting to the "exploitation" of his daughter's name and of her "personal and property rights in the attempt to increase the sales of her mother's book." A lawsuit was threatened if Molly's name remained in the title. At the same time Fast served a motion for a modification of the divorce decree against his ex-wife, demanding she seek court approval if she moved outside of four designated Connecticut towns, including Fairfield, where Fast makes his home. Jong, 42, professes shock at Fast's actions, especially his objection to her book's title. "Jonathan knew the title for a long time, had seen artwork and never voiced any earlier objections," contends Erica, who had been divorced twice, from a fellow student and a child psychiatrist, before she married novelist Fast in 1977. (They split four years later.) "I didn't make a light decision about using Molly's name. There is a long and venerable tradition of kids' books being named after real children. I discussed the impact the title would have on Molly with other writers, psychologists and psychiatrists. All the feedback was positive."

Presses stopped rolling once New American Library received the letter from Fast's attorney. After many deliberations and consultations with Jong, NAL changed the title to Megan's Book of Divorce. "It was a pragmatic decision," explains Jong, who nonetheless has filed a $4 million harassment suit against Fast, complaining that he had, among other things, "maliciously" caused her to "suffer mental and emotional distress."

Earlier, Jong says, she and Fast, 35, were on semifriendly terms. "Visitation was always open and easygoing," she says. Jong now lives in Westport with her boyfriend, Chip Sweet, 26, an aspiring actor, and recently bought a brownstone in Manhattan, where she has enrolled Molly in a private school for next year. "From the time we were divorced, Jonathan knew I always intended to live in New York during the school year," explains Jong. "He took Molly to school exams and interviews there and filled out papers. All of this was long planned with his help."

Last year Jonathan married attorney Barbara Grace, who recently gave birth to a son. Fast refuses to discuss his legal battle with Jong. "It's something that has to be decided in court," he says.

Ironically, Jong's book portrays people coming out of a divorce and remaining friends. In the final chapter, Mommy and Daddy and Mommy's new boyfriend and Daddy's new girlfriend are all sitting down to a wonderful happy brunch together, toasting each other with Bloody Marys. And Megan is happy because all the adults have stopped fighting. For now, at least, Molly can only imagine such a scene.