Shania Twain's husband cheated with her friend. She turned to the friend's husband, and married him.

Shania Twain has always been open about how the happiest chapter of her life came after one of her most painful experiences.

"I am actually grateful for what I've gone through and wouldn't change a thing," she wrote in her autobiography From This Moment On. "Although I admit I wouldn't want to live it over again, either. Once was enough."

It's a reflection that only makes sense when you understand just how entangled and public the collapse of her first marriage was.

And how unexpectedly it led her to the man she would eventually marry.

Watch: The trailer for 'Shania Twain - Not Just A Girl.' Post continues after video.

When Shania met record producer Robert John "Mutt" Lange in June 1993, her career was still finding its footing.

Lange had heard songs from her debut album and offered to produce and co-write her next project.

Professionally, the partnership was transformative. Personally, it was immediate.

They married that December.

Over the next decade, Lange would help shape the sound that turned Shania into one of the most successful artists in music history.

In 2001, they welcomed their son, Eja. To the outside world, the marriage looked solid, even enviable.

Behind the scenes, their lives had become deeply intertwined with another couple.

In the 1990s, Shania and Lange moved to Switzerland with their young son. She hired Marie-Anne Thiébaud as her assistant. Marie-Anne was married to Frédéric Thiébaud, a Swiss executive for Nestlé, and the two families grew close.

Which is why what happened next felt so incomprehensible.

In the summer of 2008, Lange suddenly told Shania he wanted a divorce. There was no clear explanation, no dramatic confrontation, just an abrupt end to their 14-year marriage.

Confused and desperate for clarity, Shania turned to the person she trusted most.

"I said, 'Marie-Anne, don't you think my husband is acting strange?'" she later told Oprah Winfrey. "And she said, 'No, I don't see anything strange.'"

What Marie-Anne didn't say was she was reportedly having an affair with Lange.

The happiest chapter of Shania's life came after the most devastating one. Image: Instagram/@shaniatwain

Lange denied the accusation at the time, telling People the split was "literally just a growing apart."

But Shania would later confirm the infidelity herself.

The truth didn't come from her husband or her best friend; it came from the other betrayed spouse.

It was Frédéric who discovered what was happening. According to reports, he found hotel receipts, phone bills and lingerie in his wife's suitcase. Faced with the evidence, he felt Shania deserved to know.

"I did discover the affair with my wife and Mutt," he told Oprah. "I said, 'Guys, now you have to tell [Shania]. This is ridiculous. You just owe her that.'"

When Shania heard, she was stunned. She still wanted to believe there was some misunderstanding.

"I called [Marie-Anne] up," she told The Ellen DeGeneres Show. "I wanted to give her the opportunity to tell me herself without me accusing her."

Instead, Marie-Anne allegedly denied the affair, and then changed her phone number, cutting off contact completely.

The betrayal was overwhelming. Shania later described the period as one of complete emotional collapse.

"I was ready to die," she said.

She sent Marie-Anne an email, pleading with her to stop.

"If you could see me crying and suffering, maybe you would have pity," she wrote. "Find love somewhere else from someone else that isn't hurting two families so much."

The stress took a physical toll. Shania was diagnosed with dysphonia, a condition that causes the muscles around the voice box to tighten.

Emotionally, she shut down.

"I didn't want to love again; it was the last thing on my mind," she told People.

The only person who truly understood what she was going through was Frédéric. Like her, he had lost a marriage, a partner and a future he thought was secure.

They leaned on each other, cautiously at first.

"We slowly became very, very good friends. We had many months of just trying to make sense of everything," Shania told Ellen.

"Holding each other up was a very difficult time emotionally for both of us. And we really found something very beautiful in the end and unexpected."

Romance wasn't immediate. In fact, Shania resisted it.

"I rejected it initially," she said. "But I couldn't control Fred's love for me and how easy he is to love."

Shania Twain is married to Frédéric Thiébaud. Image: Instagram/@fred_thiebaud

What ultimately changed things was watching how Frédéric handled the scandal and pain.

"I got to observe Fred going through the same thing I was, and I admired how he handled it," she told Redbook. "That is where I fell in love with him, because he was so exemplary in every way."

By 2009, they were officially dating. In December 2010, they got engaged. Just weeks later, on New Year's Day 2011, they were married in a small sunset ceremony in Rincon, Puerto Rico.

"My closest friends and family say they haven't seen me this free-spirited and happy in years," Shania told People. "And it's true. It's definitely true."

She described Frédéric as "a true gift to me as a compassionate, understanding friend," adding that "an amazing love has blossomed from this precious friendship."

Today, the couple live in Switzerland, near where they first met. They share a home overlooking mountains and a lake, and a black horse named Hermès.

In 2017, Shania released Life's About to Get Good, a song inspired by the joy she found after surviving what once felt unbearable.

It's a love story forged in betrayal, grief and loss, and rebuilt into something beautiful.

Feature Image: Instagram/@fred_thiebaud