In 2008, Twain and then husband Mutt Lange were separated after Lange had an affair with Twain's best friend, Marie-Anne Thiebaud. Shania confesses she "didn't see" the affair coming. "The fact that my friend betrayed me was a shock."
The deception rocked her to the core and put the singer through a rough period to which she says she cultivated a "never again attitude" towards marriage. She tells Nancy she "had enough with love" until finding solace with her ex best friend's husband, Frederic Thiebaud.
A close friendship began, and although Twain says she told him that falling in love with him was "never going to happen," she admits she couldn't "prevent those things," and the two became romantically involved in 2009.
Known as one to value her privacy, Twain made the surprising decision to sign on with the Oprah Winfrey Network for the reality series "Why Not?," to which the season finale will showcase her January 1st Puerto Rican wedding ceremony.
Watch the interview to hear Shania in her own words, and don't miss the season finale of "Why Not?" when it airs this Sunday, June 6th, on OWN.