To an observer it might have looked like the perfect Father's Day tableau: a dad and his daughter, munching on deli sandwiches and watching a soccer match on TV. But when actor Ryan O'Neal got together with his often-estranged daughter Tatum on June 16, the only ordinary thing about the scene was the cold cuts. Although the elder O'Neal, who was diagnosed with leukemia last year, was feeling healthy thanks to the anticancer drug Gleevec, his daughter was thin and shaky, the result of coming off a six-month cocaine bender. And despite nearly four decades of pain between them, the conversation never turned deep. "We're not going to do that talk," Tatum says flatly. "Different generations."

Ryan O'Neal may prefer to keep family secrets to himself, but his troubled daughter is finally -- and loudly -- breaking her silence. Prompted in part by a new memoir written by her ex-husband, tennis ace John McEnroe -- in which he portrays Tatum as an emotional tsunami -- the 38-year-old O'Neal pulls no punches as she looks back on a life that makes the most shocking E! True Hollywood Story look like Sesame Street. Abandoned by an overwhelmed, drug-abusing mother at age 7, she was an Oscar winner at 10 and began using drugs by 14, moving from marijuana, Quaaludes and cocaine to, years later, heroin. With her father caught up in the celebrity scene of the 1970s, a teenage Tatum and her younger brother Griffin were left on their own in Ryan's Malibu house while their father moved in with actress Farrah Fawcett. Then came her failed six-year marriage to McEnroe, 43, toward whom she remains openly hostile. Worst of all is the loss of her children Kevin, 16, Sean, 14, and Emily, 11: When O'Neal became a heroin addict in 1995, McEnroe took control of their kids and has retained it ever since. "Not being able to see my kids is like part of me is missing," she says. "Part of my soul is missing."

And yet, even though many of her troubles can probably be traced to her chaotic childhood, O'Neal retains sympathy for the man who might have made things better: her father. When she learned by phone in April last year that Ryan, 61, had been diagnosed with cancer, "I told him how much I loved him, how much he had given me," she says. "He's the love of my life."

O'Neal speaks far less warmly of her ex-husband, whom she calls "the main stress for so long that I can't count anymore." After years of bitter battling over their children, the pair are at loggerheads again over McEnroe's bestselling memoir You Cannot Be Serious. O'Neal claims he misrepresents the way their marriage ended and generally casts her in an unflattering light while minimizing his own faults. Although she concedes that he is generally a good father to their children and that "most of the stuff (in the book) is true," O'Neal says she resents the invasion of privacy. "He crossed the line, and I feel like it's time to fight back," she says. One tactic: She has made public a transcript of a 20-minute 1999 phone argument with McEnroe regarding their children's vacation plans that O'Neal secretly taped and submitted in court as part of her custody case. During the conversation a foulmouthed McEnroe -- barely a line goes by without a curse -- tacitly admits to smoking pot and berating and even hitting one of their children. At one point, McEnroe screams that he is not going to let their kids "go down the tube because they got a f------ wacko as a mother."