FORMER Australian Idol winner Casey Donovan has revealed she was madly in love with a man named Campbell for six years — only to discover that he never actually existed.

Donovan reveals the bizarre and heartbreaking story in her new autobiography, Casey Donovan: Big, Beautiful & Sexy, excerpts of which are published in this week’s New Idea.

The 25-year-old singer shot to fame at the age of just 16 when she won the second season of Australian Idol, but was still struggling with teenage insecurities about her weight and her looks.

Her ‘romance’ with Campbell started with a phone call while she was on tour with her fellow Idol contestants in 2004.

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Her mysterious admirer claimed a mutual friend had passed on her number. At first, Donovan was unimpressed, but the mystery man soon won her over with questions about her life and interests.

“Oddly, with every question I became less impatient and relaxed into the conversation. After a while it even felt like talking to an old friend. Before I realised it, I’d been on the phone to this guy for over an hour.”

A budding phone friendship developed, and Campbell then introduced Casey to his friend Olga, who arrived at Donovan’s house one day in her friend’s place because he was supposedly ‘too drunk to drive’.

That was just the first of many excuses from Campbell. Each time Donovan pushed for an in-person visit, there was a fresh excuse.

“He had to go to Queensland to look after his sick aunt, his car wasn’t working, his cousin died, his sister was pregnant, someone broke into his house, he had to go up the coast to see his godson, he was out of town on business,” she writes.

Whenever her telephone relationship with Campbell faltered, their intermediary Olga — who was “stocky and intense when she spoke; it was like a child stuck in a woman’s body” — was there in person to pick up the pieces.

At Campbell’s insistence, Donovan even had sex with Olga. Donovan has previously denied rumours of same-sex attraction, telling the Star Observer in 2010, “I do like boys. I’m very open about my sexuality — I like guys.”

“All I felt was dirty … uneasy and used. I was so ashamed of the person I had become, always considering Campbell in everything I did,” Donovan writes of the increasingly strange relationship in her book.

Donovan’s suspicions were finally roused one day when she discovered a SIM card that supposedly belonged to Campbell on the floor at Olga’s house.

By that stage, Donovan’s career was on the up, thanks to her starring role in the stage musical The Sapphires. Her self-esteem was boosted too, and she cut all ties with Campbell for the last time.

After the split, Donovan finally told the whole strange story to her manager Jason Williamson, who immediately twigged that Olga and Campbell were one and the same person. Confronted, Olga soon admitted there was no Campbell.

“At first she tried to defend herself, but once there was silence she started to cave in and her true colours began to show.

“In the end, Olga did confess that she was Campbell. I finally heard it from the devil’s mouth. But she never came close to explaining why she did it. I still don’t have that explanation.”

“I spent six years of my life loving someone who never really existed, being ‘supported’ by a best friend who was deceiving me from the beginning, pulling all the strings. I know everyone gets their heart ripped out every now and again but that … That just took the cake for me!”

Since the ill-fated relationship came to an end, Donovan says she’s preferred to focus on her career, although she has dabbled in online dating.

“I won’t let love lead me astray again,” she said. “I will find out if they’re real or not first!”

Casey Donovan: Big, Beautiful & Sexy (New Holland, $29.95) is out on March 1.