Sarah Jessica Parker became an icon to a generation of women playing unlucky-in-love Carrie Bradshaw – but in real life, she seemed to have the marriage thing down pat. Now friends of the Sex And The City star reveal her 15-year union – a lifetime in Hollywood terms – with 1980s heart-throb Matthew Broderick has been under strain for years.

Those close to the two say Sarah and Matt have been living apart for months as they prepare their children, nine-year-old James and twins Marion and Tabitha, 3, for the inevitable. And it’s all Sarah can do to keep it together for them. “Sarah’s terrified of being alone with three kids,” a source close to the couple tells Woman’s Day. “She knows her marriage hasn’t been right for a long time. But at the same time she feels like she’ll never meet anyone else, and she’s chain smoking and crying a lot. She doesn’t know how to cope. She is devastated.”

Dealing with a marriage in crisis is sadly nothing new for Sarah, 47. Back in July 2008, a US magazine reported that Matthew had been having an affair with a 25-year-old redhead while Sarah was filming the first Sex And The City movie. Despite her angst, the marriage survived – but not long after the twins were born via a surrogate in 2009, the relationship began to splinter again.

“Sarah is the first to admit she was a career woman who took her time to get into family mode. And although they coped with the arrival of their oldest child James, having the girls put a massive strain on their relationship,” our insider says. “She has a cleaner and nannies, but she gets frazzled trying to combine work, kids and making her marriage work. Matthew is a great dad and he’s very supportive – he used to cook almost every meal – but even so, they ended up fighting a lot and Sarah doesn’t have much patience for that.”

Read more about Sarah and Matthew's marriage in this week's Woman’s Day on sale Monday October 22, 2012.