To play the adulterous Justine in The Good Girl, Jennifer cheated on Friends and suffered bad hair and a near-breakdown. "I was losing my mind," she tells Empire.

  There were tears of joy recently. Some polite moisture as Jennifer Aniston became the first Friend in nine years to be honoured with a lead actor Emmy, the television equivalent of the Oscars. One year previously, however, while she was recording that award-winning season of Friends and simultaneously moonlighting on indie comedy The Good Girl, the tears were of an altogether different kind.

  "I don't think I've ever cried on a set before. And we would break down; we'd have cry-fests. It was just so...much. "Jennifer Aniston is brunching with Empire in the upscale ski resort of Sundance. We are discussing her emotionally exhausting but brilliantly unaffected work in Miguel Arteta's dark comedy of adultery. NB: she is not joking. "I was losing my mind. We would have moments of looking at each other and going. 'Miguel is crazy. This is insane. This is not human. This is not civil.'"

  Thirty-three year old Jennifer Aniston is in many ways the only Friend with a career to speak of. Courtney Cox Arquette may have been in the biggest box office hits (the Scream trilogy). Lisa Kudrow may have the indie factor (The Opposite Of Sex, Bark) on her side. And David Schwimmer is possibly the better actor (Band of Brothers, Apt Pupil). But of all the movie projects launched on the back of Friends (Ed, anyone?), only Aniston's seven or so lead credits, notably the romantic comedy trilogy she made in 1997 and 1998, 'Till There Was You, Picture Perfect and The Object Of My Affection, have achieved any respectable level of success.

  These formulaic, modest hits were churned out when the popularity of Friends, and Rachel in particular, was at its peak. She was not yet Julia Roberts, but she was a younger, hipper alternative to Meg Ryan. There was only one problem: the movies weren't much good. A hard truth Aniston readily acknowledges. "At first it was like, 'A movie? Yeah! I'll do it.'" She laughs at her own innocence. "Before you even read a script! But you learn those lessons. And I don't have any regrets. Well..." A perfect comedy pause. "No."

  Aniston, however, remained keen to get off the rom-com treadmill: "Things get thrown at you," she reasons, (but) there are only so many ways to tell a love story." Proof that Aniston was "getting better" at reading scripts was her involvement with Mike judge's underrated 1999 comedy, Office Space. But even as Survivor eclipsed Friends in the US, Aniston found it hard to be accepted as anything other than little-miss-perfect. "My flight has always been to get out of the Rachel shadow," she says simply. "Not to begrudge that because God knows, it's been heaven. But y'know, we're actors."

  Mike White and Miguel Arteta, the independent writer-director team behind Chuck & Buck, could afford no such preconceptions. To get The Good Girl made they needed a name attached to the lead part. It did not matter that the dowdy, bored, unhappy housewife who embarks on a doomed affair with a disturbed younger man and spirals out of control was the opposite of Rachel Green. They needed a name.

  When Mike White's sharp, uncompromising script arrived through the Pitt-Aniston letterbox she was convinced it was a mistake. "I couldn't believe they were on board with the idea of me." This might strike jaded observers as somewhat disingenuous, but let it be noted, Aniston was so keen on the role of Justine Last that when it fell outside her norma summer hiatus from friends, she signed on anyway. Even under optimum circumstances, the combination of a typically tight indie shooting schedule and a very demanding part would be punishing. But with her weekends spent working on Friends as she did the film, Aniston was close to cracking up. "I would never do it again," she winces. "Truly. It's not worth it. My sanity and my private life are too important to me."

  Co-star Jake Gyllenhaal remembers the dusty ground with the demanding Arteta as being so tough it became funny. "She would break down doing a scene and Miguel would come over and say, 'That's awesome! So good!'" In fact, for an actress famous for her haircut, the only thing easy about Justine turned out to be make-up. "Oh, it was a relief," she says of the unpolished locks. "Hair and make-up was easy!"

  It's perhaps ironic that what turned our to be award-winning work on Frinds came at a time when Aniston was so drained by The Good Girl, she could "kind of walk through" her part. Now if only that other august Academy would see to reward what is definitely the best work of her career...Then we would really see some tears.

  The Good Girl is released on January 10.