EXCLUSIVE: Radar Reveals the Real Story Behind Hollywood's Most Toxic Relationship — Between Marilyn Monroe and Joe DiMaggio

On the night before her 1962 death, Marilyn Monroe had an intensely emotional phone conversation with Joe DiMaggio Jr., RadarOnline.com can reveal.

Although she'd long ago split with Joe Jr.'s dad, the screen siren remained close with her ex-stepson, 20, who was enduring a painful breakup of his own with a girlfriend.

"He had been dumped, so he was heartsick, and he called his Mom, so to speak, for consolation," said Joe Jr.'s ex-wife, Dawn D. Novotny. "Any time he had a problem you'd talk to a parent about, he'd talk to Marilyn."

Her undying devotion to Joe Jr. mirrored her true love and unbreakable bond with his father, even seven years after their devastating divorce. "Joe was the love of Marilyn's life, and she was his most profound relationship," said J. Randy Taraborrelli, author of The Secret Life of Marilyn Monroe.

Their romance was the most glamorous and dramatic of the 20th century, yet it was star-crossed.

When they met in 1952, Joe Jr. was an American pop-culture icon who'd retired after a historic baseball career and was looking for a traditional wife to cook, clean and take care of their kids; Monroe was a Hollywood bombshell whose career was skyrocketing.

While she yearned to have children of her own, she proved tragically unable. Jealousy and obsession fueled conflicts as explosive as their passion for each other, and the marriage was destined to last less than a year.

But their love for each other endured forever, and now family and friends are opening up and sharing new details about their relationship, including what drew them together, tore them apart and kept them tethered for life.