Generally speaking, it's impolite to weep after sex. But if anyone's earned the right, it's Kim Cattrall, because this time was one for the ages. It lasted six years, she gave an award-worthy performance and, as Cattrall herself knows all too well, she may never have it this good again. So go ahead, Kim, have a nice, long cry. It's the very last day of filming on the very last episode of HBO's "Sex and the City," and Cattrall is about to shoot her very last scene as Samantha Jones, the show's brazen sexual conquistador. This season, Samantha has been fighting breast cancer, and her rotating gallery of wigs has become one of the show's most bittersweet jokes. In her final scene, Samantha stands before a group of cancer survivors and defiantly yanks off her wig, revealing the bald head of a chemo patient. The director yells cut. The crew roars, giving Cattrall a standing ovation. And that's when the tears begin.

After "Sex and the City's" finale this Sunday, it'll be our turn to reach for the Kleenex, and not just because a trailblazing sitcom is saying goodbye. Given Hollywood's lousy track record with actresses in their 40s, we might not see much more of Cattrall, despite her multiple Emmy nominations. Just ask her. "It's no real mystery that women of a certain age tend not to exist in Hollywood," says Cattrall, who's 48. "Before this show, I was dealing with that. There were no roles for 40-year-olds, and if there was, it went to Michelle Pfeiffer. I love Michelle, but what about the rest of us?" It's an especially bitter pill considering that this last season of "Sex" has been by far Cattrall's finest. Without lapsing into sentimentality, she's brought both guts and vulnerability to Samantha's bout with cancer, deepening a performance that, in the past, could be a bit one-note. "One thing I regret is that the changes in her character didn't happen sooner," says a top Hollywood producer who's a friend of Cattrall's. "Maybe it wouldn't have made a difference [for her career], but I became an even bigger fan watching her handle that story line with the same class and savvy she did everything else on the show."

Back in the makeup trailer, Cattrall is wiping away a few last tears and getting her hair restyled when Sarah Jessica Parker walks in to prep for her final scenes. The two women do not greet each other. For years, rumors have flown that the "Sex and the City" cast members are not, to put it delicately, as tight as their characters are. Given that "Sex's" strength has always been its ensemble cast--three of the four leads have earned Emmy nominations--and that the show is about the bonds of female friendship, Parker's dominance in the media and in HBO's ad campaigns surely caused a hurt feeling or two. But if that's the case, Cattrall isn't copping to it. "I think we all had our moments to shine," she says after Parker departs. "Sarah was the main character, and of course that meant she got a lot of the attention. That's the business." (Another touchy subject: Parker, who's an executive producer on the show, will also get residuals from DVD sales and rebroadcasts; her three costars will not.) And if the cast wasn't out partying together after work, there's a simple explanation. "I'm 10 years older than the other girls, and they were either married or involved with kids," says Cattrall, who's single and childless. "I think every woman thinks about the mother thing and wonders if she did the right thing by working so hard and not taking time for it. But I'm finally at the point where I feel happy with the life I have. Motherhood just wasn't in the plan."

While Parker is often spotted pushing a baby stroller around New York's West Village, Cattrall's personal life moves at a quicker tempo: she spent the holidays on P. Diddy's yacht, sailing around St. Barts and Anguilla with pals Mary J. Blige, Eve and Naomi Campbell. "The only thing I wasn't ready for is the way P. Diddy loves to have fun," Cattrall says. "At 2 a.m. on New Year's, I headed to bed. By the time I had on my pajamas I got a knock on my door, and another party was about to begin. I just couldn't hang." P. Diddy himself disagrees. "Kim is a fly woman with amazing talent," he says. "I don't want to stop seeing her onscreen just because of a number." Neither do we.