SHE IS ATRUE DAUGHTER OF THE SOUTH, AND LIKE GENERATIONS of steel magnolias before her, she has come through a rough patch with her humor intact, complexion creamy and not a hair out of place. "I'm movin' up," vows the Gaffney, S.C.-born Andie MacDowell, after what she describes as a "rough" 1999, in which she separated from her husband of 13 years, model-turned-contractor Paul Qualley, father of her three children, "I was unhappy and looked horrible," she says. Not a chance. The glorious curls ("I wish there was a button I could push to have straight, swishy hair when I wanted it") still cascade around a face that landed her on magazine covers and in movies (including last year's The Muse
). For proof of her undiminished appeal, the L'Oréal pitchwoman can just report to the set of her next project, an as-yet-untitled comedy filming this summer in England. "I actually have an affair with a 23-year-old boy," says MacDowell, 42, with a laugh. "It's a great women's picture." MacDowell's sister Julia Fleming, 49, an interior designer, says there's no reason why a young man wouldn't be attracted to Andie. "When she was in her 20s, she had a round face," says Fleming. "Her mature-looking face is even prettier. The best is yet to come," To keep in shape, the 5'8" MacDowell prefers the ab machines at "the regular old YMCA, nothin' fancy," she says, and joins pals for two-hour walks near the Asheville, N.C., house she shares with son Justin, 13, and daughters Rainey, 11, and Sarah Margaret, 5. (Qualley lives nearby.) "I try to do something every day but Sunday," she explains. "It's not completely vanity, it's also my sanity." But if either ever fails her, there is a Plan B. "When people don't like the way I look anymore, or I can't grow old gracefully, I'm just going to plant flowers," says MacDowell. "I love to garden. I'd be happy as a clam, hangin' out in the yard."