By Monica Antonio (media@latinospost.com) | First Posted: Sep 13, 2015 06:52 AM EDT

During the peak of her career, three-time Olympian runner Suzy Hamilton had it all: numerous sponsorships, endorsements, a happy marriage life with her longtime partner Mark and a healthy daughter. But in the season premiere of "20/20," the blonde sweetheart of the Olympics shared how she decided to lead a double life of becoming a Las Vegas call girl, per ABC News.

In a sneak peek of the interview, aired via "Nightline," Suzy opens up about her double life and the struggles she endured to come to such a decision, including the incident during the 2000 Sydney Olympics where she staged her fall. As her popularity grew, the amount of pressure to win an Olympic medal also grew.

She said, as per People, "The whole entire world was watching me. That dream of having an Olympic medal was gone and instead of finishing the race, like most runners would, I told myself 'just fall' and I fell immediately, it just happened like that. I pretended I was injured and I remember thinking, again, 'You're the worst person in the world. Look at what you just did.'”

People further notes that after the incident, she and her husband returned to Wisconsin to start a real estate business but Hamilton slowly slipped into depression. In the advance teaser released via "Nightline," Mark told host Elizabeth Vargas that for the first time he saw anger in Hamilton. He also added that during that period, they lost the "spark."

To revive their fading intimacy, Hamilton suggested going to Las Vegas for their 20th anniversary, where she then suggested having a threesome, and, according to Hamilton, that made her feel alive.

"That was that light bulb moment in my head, 'Wow, why shouldn't I get paid for sex?'" she said.

After going home, Suzy missed the thrill and excitement and told Mark that she would go back to Vegas alone. Suzy assumed the screen name "Kelly Lundy" and began living her double life.

"One day I'd run a half marathon in the morning, in a different state, hopped in an airplane, got to Vegas, had five appointments." And by appointments, she clarifies to Vargas that this means clients.

However, Hamilton's secret was revealed to the public when an investigative journalist leaked her story. The incident pushed her to seek professional help, and she was diagnosed with bipolar disorder.

"My bipolar was driven toward sex. It could have been driven towards drugs and alcohol, or gambling. I found sex was the biggest high to fuel my mania, which is common with bipolar people," Hamilton revealed to another report from People.

More details about the former Olympian's life are revealed in her new memoir, "Fast Girl," which hits bookshelves on Sept. 14.