From PEOPLE Magazine Click to enlarge
When Tatum O'Neal's phone rang last September, the familiar voice on the other end simply said, "Tatty, this is your father, Ryan. Love Story." It was a silly joke from the actor (who starred in the hit 1970 tearjerker), one that hid the pain of their bitter 20-year estrangement. When father and daughter met for lunch one week later at a Malibu restaurant (along with Tatum's son Sean McEnroe, who'd played peacemaker), Ryan did a doubletake when she walked in. "It was as if time stood still," he says. "She's so happy. This is a different person than I remember." Over a two-hour lunch of salmon and pasta, they finally began to talk. "He told me he's sorry," says Tatum, 46. "He's all I have in terms of family, and I needed him in my life. My dad was absolutely everything to me."

Her emotional reconciliation with Ryan is just the latest example of how Tatum has used hope and healing to finally put decades of darkness behind her. Since making history in 1974 as the youngest-ever Oscar winner (then 10, she won for Paper Moon), her well-publicized decades-long battle with drugs had been a source of crushing pain. In 2008, at her lowest point, she landed in a Manhattan jail after she was arrested for trying to score a bag of crack cocaine. The oldest of Ryan's four kids (her late mother, actress Joanna Moore, was an alcoholic and amphetamine addict), she was abandoned by her father at 16, when he left her and brother Griffin to move in with girlfriend Farrah Fawcett. "I feel very lucky that I survived," Tatum says now. "I've fallen down along the way, but I've always gotten up."

Today Tatum says that, despite the slip-up in 2008, she's "fully recovered" and devoted to a 12-step program. Sipping an iced coffee in her cozy two-bedroom Hollywood apartment, she's focusing on rebuilding her acting career: In addition to the recent Joan Jett biopic The Runaways, she recently wrapped two independent films and next month returns for the next season of FX's Rescue Me, playing Denis Leary's acerbic sister. She's also working on being a good mom to her three kids, Kevin, 24, Sean, 22, and Emily, 19. (Their father is her ex-husband, tennis legend John McEnroe, who raised them after a vicious eight-year custody battle that Tatum says "took the fight out of me.")

It was Sean, a theater major studying in L.A., who first reached out to Ryan a year before Fawcett's death last June. (Fearing her father would sink into isolation and depression, Tatum gave her son Ryan's number.) About nine months before Fawcett died, Tatum herself had extended an olive branch to her, bringing her orchids and food. The two talked for the first time in years. "I had never just sat with her alone," Tatum recalls. "We laughed a lot. She seemed really grateful I was there and genuinely touched."

Fawcett's death played "a very big role" in her reconciliation with Ryan, says Tatum. "She brought us back together." Afterward, Tatum realized it was time to make amends with the man they had tumultuously shared. "God forbid something were to have happened to my dad," she says. "I don't know if I could have lived with myself." As for the brief, and now infamous, run-in with Ryan at Fawcett's funeral, where he first tried to hit on her before realizing who she was, she says, "He's a jokester. So 'Hey babe, want to get a drink?' was making a joke to a blonde woman he didn't know. I thought it was pretty funny." His legendary temper, of which she was often the target, however, hasn't been easy to laugh off. She detailed their dysfunction in her searing 2004 autobiography A Paper Life, and she says, "I feel sad for him. He has to live with himself and that's probably harder."

For Ryan, 69, their reunion was a painful realization of his own failures as a parent. "I might have been able to help her," he admits. "She didn't have anyone after her mother died. She didn't want me, and she said I abandoned her, and I did. . . . A lot of harsh things were done." But now, he adds, "we're starting over and no looking back."

Tatum is also trying to help her half brother Redmond, 25, the troubled son of O'Neal and Fawcett, who is in a long-term rehab facility after battling his own drug addiction for years. "My heart breaks for him," she says sadly. "I want him to survive. But he has a lot to go through to get better." She visits him regularly and takes him to 12-step meetings. "I want to be an example for Redmond," she says, "let him know there is someone in our family who can be sober and he can lean on me."

It's a battle she knows all too well. She is still haunted by her arrest in 2008-she pleaded guilty to "disorderly conduct" and charges were eventually dropped. "It was horrible," she says. "That was the last time I tried to get hard drugs. I felt very ashamed and embarrassed. I'm just glad that my kids forgave me."

In the end her children's love has been the greatest healing force in her life. After some 20 years in New York City, Tatum (who is single but says, "It would be great if I met someone") relocated to L.A. last summer to be closer to Sean and to daughter Emily, who attends college in San Francisco. "She is having the life I would have loved to have myself," says Tatum proudly. She says Sean recently told her, "You don't have a bad reputation, Mom. All you've ever done is hurt yourself. People root for you and want you to get better."

And now she's doing just that. "I feel more whole now that I have my dad back in my life," says Tatum. "I'm doing really well-and I'm having a blast."