David Vaughan knew there was trouble in paradise—or rather, London's Primrose Hill. Maybe it was the concern his daughter Sadie Frost, 37, and her husband, Jude Law, 30, had felt when their son Rudy was born six weeks premature on Sept. 10. Or the scare they had weeks later when their daughter Iris, 2, took an Ecstasy pill she found on the floor at a birthday party. When Vaughan, 58, an artist in Manchester, came to visit in December, he sensed "there was something up" between them, he says. "But at least then she was her usual fiery self."

Not for long. On Jan. 20 Frost was admitted to the UCLA Medical Center for what her publicist calls "postpartum depression." She checked out three days later and spent a few more days at London's Cromwell Hospital. Back home last week with Law and their kids—Finlay Kemp, 12 (her son with her ex-husband, pop star Gary Kemp), Rafferty, 6, Iris and Rudy—she faced more distress: British tabloid reports that she had tried to commit suicide in L.A. and that her husband was romancing Nicole Kidman, his costar in the drama Cold Mountain. Kidman's rep called the charge "a salacious lie." Law deemed the stories "mean-spirited and untrue." And Frost dismissed them as "complete rubbish."

Vaughan isn't so sure. Though Frost's rep denies she attempted suicide, her father tells PEOPLE that she "scratched" her arms in L.A: "The poor soul was trying to say, 'Look, I'm hurting.' She's having the kids while he's off making films. They don't have time to understand each other." But her decision to get help, he says, means "the situation isn't past the point of no repair."