“American Idol” Alum William Hung's Marriage Imploded amid His Gambling Addiction. How He Survived Rock Bottom“ ”(Exclusive)

Twenty years after going viral with his 'American Idol' audition, Hung opens up to PEOPLE about overcoming his darkest moments — and how he found a new start

William Hung certainly never set out to become a viral sensation.

But when he auditioned for American Idol in San Francisco in 2004 during the show's third season with an off-key rendition of Ricky Martin's "She Bangs," that's exactly what happened to the UC Berkeley engineering student.

"It was all very surprising," Hung, now 41, tells PEOPLE of becoming a household name after his audition, which aired on Jan. 15, 2004. "I didn't expect that. I had no expectations going in other than thinking that it was going to be fun."

Hung's audition was memorable for a number of reasons. Then only 20 years old, he had been living in the U.S. for 10 years after immigrating with his family from Hong Kong. He had a childlike innocence about him that the cameras loved.

Hung remembers producers sought him out for a pre-audition interview, and when he walked out onstage he told the judges that singing was his passion.

"I may not be the best singer, but I sing from the heart," he told judges Paula Abdul, Randy Jackson and Simon Cowell.

Viewers held their breath, hoping Hung might be the next unexpected musical sensation: Someone who didn't look the part of a typical pop star but had undeniable talent.

Related: Randy Jackson Reveals How He's Maintained 100 Lb. Weight Loss 18 Years After Gastric Bypass Surgery

That didn't happen.

Hung's off-pitch singing and quirky dance moves had the judges laughing from the start. After his performance, Cowell — famous for his stinging criticism — told Hung it "was one of the worst auditions we've had this year."

"I mean, everything about it was grotesque," Cowell underscored.

Cowell's criticism was mean, but the words didn't seem to bother Hung. "I already gave my best and I have no regrets at all," he told Cowell, earning him praise and encouragement from Abdul and Jackson.

Today Hung still maintains that upbeat attitude — and he believes it's why he got famous in the first place.

"Most people would be angry or upset, or throw their water bottle at him," he says. "I didn't see the need to do that, and people seemed to like it."

His TV moment altered the course of his life.

Hung dropped out of Berkeley and actually pursued a musical career. "I had my moment at the top," he says of singing. "My first album, Inspiration, was the No. 1 independent album on the Billboard charts."

Related: The Most Memorable Contestants of 'American Idol': Where Are They Now?

He also had bit roles on shows like Arrested Development (he played himself) and starred in several commercials. He appeared in a few Chinese films and also became a motivational speaker.

But soon the music and entertainment industry stopped calling.

"In this situation, very few people can stay on top for long," he says of viral fame. "So after a little while, I thought, I don't want to waste my life, so I went back to school, finished my degree and looked for a stable job. That was OK with me. I'd already gotten more out of American Idol than I ever could have expected."

After earning a degree and MBA in mathematics, Hung took a job at the Los Angeles Sheriff's Department, where he worked as a statistical analyst. "I like data, playing with numbers and computers, so it was something I enjoyed," he says.

But another career was calling.

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"I quit my job three years ago and became a professional poker player," he says with a laugh. "I'd been doing it on the side for a while, and I decided maybe I was good enough to go for it. I was earning way more doing that than I was at my regular job. It was going well for a while."

And then it came crashing down.

"Unfortunately I developed a gambling addiction," he says. "I knew I was good at poker, but then I got greedy. I got into sports betting. The whole gamut. I know better [now]. I wasn't supposed to do those things, but I did it anyway," he says. "And I paid for it. I got divorced, and I learned I had to be smart about which risks I chose to take."

In a candid post on his LinkedIn profile about a year ago, Hung told his followers that it was "time to deal with" his addiction.

"Things went downhill fast when my ex-wife found out about you," he wrote in a latter addressed to his gambling problem. "I came home from work one day, and she started asking me all these questions about why I was so nervous about every sports game and why I was always tired ... How do you think that went — with all of the money I could have used to improve our life — gone? I'll give you a hint: it ended with her asking for a divorce."

Related: Fantasia Barrino on Her Personal Struggles After American Idol: 'I Lost a Lot' (Exclusive)

Once again, Hung picked himself back up.

He married his third wife Hannah last year and decided to go back to his old job analyzing data for the Sheriff's Department.

He's also hoping to start a family. "It's a work in progress," he says of trying for a baby with his wife.

After overcoming his ups and downs, Hung is excited about the future and says he'll continue to pursue entertainment endeavors on the side (he says he's very popular on Cameo).

But these days stability is what's most important to him. "There's nothing wrong with having a steady job after fame," he says. "I think it's the right thing to do, to provide for my family now."

Related: Simon Cowell Makes Rare Appearance with Son Eric, 9, at America's Got Talent Finale — See Photos!

As far as his motivational speaking engagements, the biggest point he stresses to people is that attitude is everything.

"I remind people to expect the unexpected, and that whatever happens, having the positive outlook in life helps. It is a choice to see the good in a potentially bad situation, or see the good in the potentially bad people who might try to take advantage of me or whatnot. That's the way I reframe my mindset. Instead of feeling bad for myself, I think, how could I make this more mutually beneficial? So I think that's the biggest takeaway from this whole experience."

Oh, and when he meets people on the street and they ask him to sing "She Bangs?"

"I have other favorite songs," he says with a laugh. "Ask me to do 'Just Dance!'"

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