The 35-year-old singer said their relationship threw her into money issues, reported Contactmusic.
When asked about some of her biggest financial mistakes thus far, Simpson replied, "The biggest money mistakes? I don't know. For some reason I thought of my first marriage!"
The former couple, who shared the same manager, first began dating in January 1999 but called it quits shortly afterwards, only to rekindle their romance five months later.
They took their relationship to the next level in February 2002 when the hunky singer popped the question, and just eight months later on October 26, 2002, they became husband and wife following a romantic ceremony in Texas.