By THOMAS WHITAKER and TRACEY KANDOHLA, THE SUN

Movie hunk Jude Law and wife Sadie Frost are living under separate roofs less than half a mile apart.

Sadie — who has been suffering post-natal depression — is staying in the couple’s new £2million house with their three children. But Jude is at their old £1million house just three roads away.

A pal of the couple said last night: “This speaks volumes about the state of their marriage. Publicly they are saying their marriage is rock solid. But behind the scenes there are serious problems which are appearing irretrievable.

“Sadie is going through the worst spell in her life. She has been in hospital for days and is desperately unhappy.”

The couple’s old house in Primrose Hill, North London, is stripped of furniture and so empty that Jude, 30, had to pop out yesterday for a takeaway coffee.

A neighbour said: “There isn’t even a kettle in the house. We thought we wouldn’t see Jude back here again.”

Road to Perdition star Jude and Sadie, 37, have tried to put on a public show of unity. On Tuesday morning they grinned for photos with the children.

But within two hours Jude left. He spent the night at their old house and returned to Sadie’s at 7am yesterday.

Jude — who only arrived back in Britain from America four days ago — left again three hours later without comment.

He has angrily denied rumours he cheated on Sadie with film star Nicole Kidman, 35, his co-star in new film Cold Mountain.

Asked about their marriage problems yesterday, Dracula star Sadie insisted: “At the moment they are fine.”

She has told friends she is not giving Jude up “without a fight.” But Jude is alleged to have told her their five-year marriage is over.

A pal said: “They need some space. Things have been very heated. It was better to spend the night apart.”

Sadie has been comforted by phone calls from film star pal Gwyneth Paltrow. The Sun told last week how Sadie needed treatment after marking her arms in “a cry for help”.

Sadie’s brother Toby Vaughan, 21, of Manchester said: “I really hope they can work things out. They both think the world of the kids and that might keep them together.”

She and Jude have a five-month-old son Rudy, daughter Iris, two, and seven-year-old son Rafferty. Sadie also has a son Finlay, 12, by her first hubby, Spandau Ballet pop star Gary Kemp.

LONDON - Australian supermodel-actress Elle Macpherson has given birth to a baby boy, her publicist said Wednesday.

Aurelius Cy Andrea, born Tuesday morning, is the second child for Macpherson, 39, and her Swiss partner, Arpad Busson. The baby weighed 7 pounds, 11 ounces.

Aurelius was born by natural delivery at the exclusive St. John and St. Elizabeth Hospital in northwest London, said Macpherson's publicist, Kimberley Witcombe. The hospital has been the favored choice of other celebrity mothers, including model Jerry Hall and actress Sadie Frost, Jude Law's wife.

"Aurelius Cy Andrea Busson will be a cherished brother to their son, Flynn, who turns 5 on Valentine's Day," the publicist's statement said.

German supermodel Claudia Schiffer left a different hospital Wednesday with her son, Caspar, who was born last week.

Schiffer, 32, gave birth to Caspar, her first child, by Caesarean section with her husband, British film producer Matthew Vaughn ("Lock, Stock and Two Smoking Barrels," "Snatch"), by her side.

Macpherson and Busson, who live in fashionable Notting Hill in west London, became engaged last year but have not publicly set a date for the wedding.