Hollywood’s Sneakiest Affairs

1. Jude Law and Daisy Wright

Jude got naughty with the nanny

Jude Law fell for Sienna Miller on the set of Alfie, and the couple got engaged on Christmas Day 2004. But only a few months later, Jude, 34, began an affair with Daisy Wright, 27, the nanny of his children with ex-wife Sadie Frost. After the nanny tattled to a British newspaper, Jude was forced to ’fess up. “I’m deeply ashamed and upset that I’ve hurt Sienna,� he said in a statement. “This is a big mess I’m not proud of,� added Daisy. Sienna, 25, called off their engagement, but eventually gave the romance a second chance — only to see it fall apart again.

2. Billy Crudup and Claire Danes

Billy cheated when Mary- Louise was pregnant

In November 2003, Billy Crudup left his seven-months-pregnant girlfriend, Mary-Louise Parker, for Claire Danes, whom he met when they co-starred in Stage Beauty. But despite a bitter breakup, Mary-Louise still named her son, William, after his father. Today, the exes remain civil for the sake of their 3-year-old. In January, Mary-Louise, 42, invited Billy, 38, to William’s birthday party at the Scholastic Store in NYC, and she reportedly allows him to babysit.

3. Keith Urban and Amanda Wyatt

Nicole and Keith had it rough

They say the first year of marriage is the hardest — and nobody knows that better than Nicole Kidman. “We’ve been through a lot,� admits the 39-year-old, whose husband, Keith Urban, checked into rehab four months into their marriage. Shortly after, lingerie model Amanda Wyatt, 23, claimed she had been having an affair with Keith, 39, for two years and that it had ended only a month before he married Nicole. “We’d drink and party and make love,� says Amanda. But the country star denies he cheated. “It means everything to me to be married,� says Keith. “I really want to do it only once. I’m very loyal.�

4. Sean “Diddy� Combs and Jennifer Lopez

Kim forgave Diddy

Shortly after Kim Porter gave birth to her first child with Sean “Diddy� Combs in 1997, she received some devastating news — her rapper boyfriend was having an affair with Jennifer Lopez. “I was so angry,� says Kim, who kicked him out of the house. “I wasn’t trying to hurt Kim,� admits Diddy, 37, “but Jennifer was my perfect match in terms of energy.� But after Kim forgave her boyfriend of three years, he rushed back to her. “He was still in love with me,� Kim, 35, says. “He just fell for a big booty and a smile.�

5. Peter Cook and Diana Bianchi

Christie’s husband cheated on her

Christie Brinkley first learned that her husband, Peter Cook, wasn’t the Prince Charming she once claimed he was in June 2006. That’s when Brian Platt — the stepfather of Peter’s then 18-year-old personal assistant, Diana Bianchi — told Christie about Peter’s year-long affair with his stepdaughter. Diana says it started not long after the 47-year-old architect met her at the toy store where she worked and offered her a $50-an-hour job. When Christie, 53, found out, she ended their 10-year union.

6. Meg Ryan and Russell Crowe

Meg fell for her co-star

She’d been known as America’s sweetheart for years, but in June 2000, Meg Ryan’s girl-next-door reputation was shattered when the star — who’d been married to Dennis Quaid for nine years — was caught cuddling with her Proof of Life co-star Russell Crowe. “I felt like the Scarlet Woman,� reveals the 45-year old. But Meg insists her marriage had been on the rocks before she began her affair with the Aussie hunk. “I did not leave my marriage for Russell, I left my marriage because it was not working,� she says. Meg and Dennis, 53, divorced that June; she and Russell, 43, split soon after, too.

7. Tori Spelling and Dean McDermott

Tori and Dean both left their spouses

Tori Spelling had been married for 14 months and Dean McDermott for 12 years when the two fell in love on the set of the TV movie Mind Over Murder in 2005. Soon after filming wrapped, the two left their spouses for each other. “I went into the marriage with the best intentions, hopes and dreams,� says Tori about her union with Charlie Shanian, 35. Dean’s wife, Mary Jo Eustace, 49, admits she “thought it was a joke� when he told her Tori was his soulmate. But it was serious: Dean, 40, and Tori married in May, and this March, she gave birth to their son, Liam. “I am having the best time of my life,� says Tori, 33.

8. Matt LeBlanc and Andrea Anders

Matt had strayed before

Matt LeBlanc made a shocking admission in June 2005 — while at a Canadian strip club, the star, who was married to Melissa McKnight, had a wild night with a dancer. Though he apologized, there was more trouble to come. Six months later, Matt, 39, left Melissa, 42 — with whom he has a 3-year old daughter — for his Joey co-star Andrea Anders. He officially separated from Melissa last April, leaving her devastated. Says a pal: “She was absolutely blindsided.�

9. Nick Carter and Ashlee Simpson

Nick played while Paris was away

When Nick Carter dated Paris Hilton for six months in 2004, he said, “I’d fallen head over heels for this chick.� But that didn’t stop the former Backstreet Boy from setting his sights on Ashlee Simpson when Paris, 26, flew to Australia to film House of Wax. Nick admits he and Ashlee, 22, “hooked up� and he was busted by the Simple Life star. Paris found out about it when she came back from Australia. Ashlee claims Nick, 27, was lying about them getting close. “When I heard that, I was dying laughing,� she says, but it was still the end of the affair for Nick and Paris.

10. Anne Heche and James Tupper

Anne fell for her co-star

No one was surprised when Anne Heche and James Tupper discovered that their undeniable on-screen chemistry in Men in Trees was just as strong off-camera. But Anne, 37, was still married to Coley Laffoon when she and James were reportedly spotted making out on a flight from Vancouver to LA. “They looked like high school kids in love,� a witness claims. James, 41, who separated from his wife, Kate, last year, insists the couple “never crossed the line� before Anne split from Coley, 33, in January, and says they connected over their failed marriages: “We really trusted each other right from the beginning.�