Jessica Simpson is more than a pop star with a pretty face and a killer voice. She has turned her name into a billion-dollar fashion empire. Simpson sat for an interview with CNBC's Kelly Evans on Closing Bell on Thursday and talked fashion business and her greatest financial  mistake — her first marriage.

The thirty-five-year-old business mogul revealed that she doesn't keep track of her multimillion dollar fortune: "I don't always know where all of my money is, but there are people that I love that know where all my money is."

Speaking of David Levin, Simpson's business manager, she said: "He's one of the first people that I met coming into New York City, and I trust him with everything. We've made really great investments, we haven't really had many mistakes."

Perhaps because of Simpson's  hit single, "These Boots Are Made for Walking," recorded on the Dukes of Hazard soundtrack, she started her fashion empire by selling high-heel shoes and boots. Simpson recalls how she launched her signature collection:

"I'm definitely a person that is all about taking a risk, and everything to me is kind of a 'Why not?' I take an opportunity by the reigns and just go for it. So when we started, it was only shoes and now it's grown so big," she told Evans.

Simpson revealed during the interview that her first marriage to Nick Lachey was costly. "The biggest money mistakes? I don't know. For some reason, I thought of my first marriage," laughed Simpson.

During the three-year marriage, Simpson had a meteoric rise to fame with the pair's reality show, Newlyweds, appearances in Hollywood movies, and a hit album. By the time Simpson asked for a divorce, she was worth more than Lachey whose boy-band fame was fading. They went into a court battle, but Lachey quit the fight accepting less than half of the marital estate, according to Forbes.

Simpson has regrouped in the past decade and has made the most of her great fortune after her marriage ended. Since then, the Jessica Simpson Collection and many other projects have made the celebrity's bank account grow.

It doesn't sound like Simpson is ready to stop at her current level of success. When asked about her plans over the next five or ten years, she quipped:

"I always say I'm ready for another billion."

Source: CNBC's "Closing Bell", Forbes