EXCLUSIVE: Break-Up That Shook the Palace: Secrets of the Moment Prince William and Kate Middleton's Fairytale Crumbled — And How They Got Back Together

It was a love story that captured hearts worldwide – Prince William, the dashing young heir to the British throne, and Kate Middleton, the beautiful commoner who seemed destined to become his queen.

But in the spring of 2007, their perfect romance came crashing down in a shocking break-up that sent tremors through the palace, and left tearful Middleton with a shattered heart and dashed hopes, and RadarOnline.com can now reveal the secrets behind their split, in their own words.

Middleton, now 43, said: "Well, I think if you really go out with someone for quite a long time, you do get to know each other very, very well, you go through the good times, you go through the bad times.

But William, 42, wanted to put the brakes on.

He recalled: "I thought we were too young. We both needed our space. We needed to find our way."

A palace insider told us: "The worst thing about their split was that after five years together, he did it in a 30-minute phone call."

The couple had met at the University of St. Andrews in Scotland. For years, they seemed inseparable.

But behind palace walls, cracks were forming.

Friends whispered that William, already struggling under the crushing weight of royal expectations, had begun to listen to warnings from his father, Charles and grandfather, Prince Philip, that he needed to get engaged or get out with other gals and "sow some wild oats."

Middleton said she already knew her prince was "drifting away" and had sensed "something was wrong" for a while.

"William was so worn down by the endless onslaught against his relationship with Kate, he didn't put up a fight," a palace source told us. "He even told Charles that he'd break the news to Kate as soon as possible, he said, 'I think it's time I do sow some wild oats.'"

Of course, Middleton was devastated, but wisely, she kept that to herself and appeared in public smiling and confident, at one point waving to photographers in an adorable tennis outfit and twirling her racket.

Party Nights

The young prince gathered his friends and proceeded to party hard at London's Mahiki nightclub, where he stood up holding a pint of ale and shouted, "I'm free." to the room full of revelers, then he slipped into a drunken version of a "robot dance," which was popular at the time.

He then told his pals that they should all join him and "drink the menu," which they did until the wee hours of the morning.

According to reports at the time, the 25-year-old prince also had his eye on someone else, socialite Isabella Anstruther-Gough-Calthorpe, but the actress and model is said to have rejected his advances because she did not want to be constrained by the inevitable demands of royal life.

"This did not cool William's ardor," explained Rob Jobson, a British journalist and author of the book Catherine, the Princess of Wales. "He reportedly tried to woo Isabella, visiting her several times at her family home. Despite his evident crush, she apparently rebuffed his advances."

Kate Fights Back

Heartsick but proud, Middleton wasn't about to let the British public feel sorry for her, and her devoted mom, Carole Middleton, supported her.

"Carole Middleton acted swiftly, taking her heartbroken daughter for a break in Dublin a welcome respite from media scrutiny," Jobson added. "On Catherine's return, she decided she wasn't going to sit around moping; what was good for the goose was good for the gander."

When nosy folks asked how she was doing, she shrugged and said: "Really, it's fine."

Now alone in the public eye, she was repeatedly photographed wearing more risqué outfits than ever before when she went out with friends.

Jobson went on: "She turned to old friends for support, going on holiday with a girlfriend to Ibiza. They partied long into the night. Back in London, there were soon so many paparazzi shots of Catherine leaving nightclubs – often with her sister, Pippa – that the media dubbed them the 'Sizzler Sisters.'"

It didn't take William long to realize he'd made a mistake.

"I had second thoughts," he admitted.

A few weeks later, they were both invited to a fancy costume party. Kate arrived dressed as a nurse, and William made a beeline for her as soon as she walked in.

The attraction was overwhelming for William, and "they then spent the first part of the evening deep in conversation before hitting the dance floor, where they ended up kissing," said an insider.

William soon realized life without Kate was a hollow existence, and she felt the same.

"There's no one quite like William," she said.

A Promise

After that night, they reunited.

It was kept a secret from the public while they consolidated their future plans. They took a long, private vacation together in Kenya in 2010 and while Kate and William were sitting side by side on a blanket during a picnic beside Lake Alice, he finally asked her to marry him.

"The question wasn't entirely unexpected, of course, but Catherine's face lit up with a radiant smile as she said 'Yes,'" said Jobson.

William later said that the reason he waited so long before proposing was to give Kate a true insight into royal life before marriage that will one day see her become queen of England.

Since then, their love has only grown stronger. When William finally slipped the sapphire ring on Kate's finger, it wasn't just an engagement, it was a victory over doubt, heartbreak and the relentless pressures of royal life.

Kate had proven her resilience – and she later said although their split was hard: "It made me stronger."

Happily Wed

Since then, their love has seen them through so much: the death of Prince Philip and Queen Elizabeth, the arrival of their babies, and Kate's terrifying cancer diagnosis and chemotherapy treatments, which, to William's joy, worked and officially cured her.

Since their April 29, 2011, wedding, the pair has been a joint force, solid in their love of each other and their kids, Prince George, 11, Princess Charlotte, 9, and Prince Louis, 6.

Kate added: "This time has above all reminded William and me to reflect and be grateful for the simple yet important things in life, which so many of us often take for granted. Of simply loving and being loved."