Like Gwyneth Paltrow and Jennifer Lopez before her, Uma Thurman couldn't keep her emotions in check after filming a kiss with Ben Affleck. But shooting the thriller Paycheck last June in Vancouver, love was in the air only because Thurman's kids—daughter Maya, 5, and son Levon, 21 months—had arrived on set as the scene was being filmed. "She went rushing down the street" to greet them, says Jackie Haliburton, owner of a clothing store featured in the scene. Being a working mom, says Thurman, "is powerful. It's not for the meek."

Neither is being a movie star, which is why nothing, not even an ill-timed public split from husband Ethan Hawke, is raining on Thurman's parade as she basks in the glow of Kill Bill: Volume 1. As the Bride, who awakens from a four-year coma to seek revenge on those who tried to off her, Thurman, 33, has found a role that she can really sink her samurai sword into. After many years of concentrating on home life instead of her career, Thurman is getting cheers for her comeback—and has surprised herself. "I'm the last person that would've thought I would ever be asked to be so tough," she says.

Making Kill Bill was anything but simple for Thurman, who was fielding calls from impatient Bill producers during her final weeks of carrying Levon in 2001. Says director Quentin Tarantino: "Uma would say, 'I'm not baking a loaf of bread here, I'm having a baby.' " Just three months after giving birth, Thurman began her three-month training sessions for the film, with one caveat: "I said, 'I will work hard, I will kill myself, but nobody can separate me from my baby.' " Says costar Julie Dreyfus, who plays Sofie Fatale: "She was nursing when she was training. I don't know how she did it."

In addition to juggling breast-feeding and butt-kicking, Thurman was also trying to shed her pregnancy weight. "She was thicker than she had ever been," says costar Vivica A. Fox. "She lost about 60 lbs. She had so many fight scenes and never complained. I complained a lot more than she did." But after the 156-day shoot wrapped, "I stopped all activity for a long time," says Thurman. "I have never been through anything so difficult."

That is until her five-year marriage to Hawke, 32, began to unravel. The couple, who fell in love filming 1997's Gattaca, have been estranged at least since August, when news broke of Hawke's relationship with Jennifer Perzow, 22, who works for her family's clothing business. Hawke and Perzow met at a Montreal restaurant early last summer while Hawke was filming Taking Lives. Returning home to Manhattan last month after shooting a Before Sunrise sequel in Paris, he moved into a hotel near the couple's apartment. He and Thurman, who met with lawyers last month, "are separated," says a source. "They're still deciding on the next step."

The split has been tough for Thurman, who has put on a brave face during her Bill media tour. "Keeping busy could be her form of therapy," says one Kill Bill source. "Her character is a really strong woman, and she wants to show her strength too." But there are cracks. "I am just trying to figure things out," she told Britain's Mirror. "You have to be brave. It's very difficult, but the pros of having a family have been amazing for me." Adds her brother Ganden, 35: "She is doing as well as can be expected."

Thurman, meanwhile, is relying on her bond with Levon and Maya. "She spends as much time with them as possible," says Ganden. "They're coming up sharp as a knife. I think it's a Thurman trait." With Paycheck due out in December, and Kill Bill: Vol. 2 to follow in February, Thurman is keeping sharp herself as she enters a new phase of both her professional and private lives. "When I went back to work after having my first child, it was difficult," she says. "I was too worried about that to be able to feel alive in my skin. And I don't feel that way anymore. I feel ready for life again. I feel great!"

JASON LYNCH
Sean Daly and Alison Singh Gee in Los Angeles, Sharon Cotliar in New York City, Brenda Rodriguez in Vancouver and Lauren Schreffler in London

  • Contributors:
  • Sean Daly,
  • Alison Singh Gee,
  • Sharon Cotliar,
  • Brenda Rodriguez,
  • Lauren Schreffler.