According to sources close to Shania Twain, the country music singer is “devastated” over her husband’s affair with one of her close friends.

Robert “Mutt” Lange’s affair with Twain’s close friend Marie-Anne Thiebaud allegedly caused their separation after 14 years of marriage. Theibaud was a secretary and house manager of Lange and Twain’s Switzerland home.

“Mutt and Marie-Anne left their spouses for each other and are still in a relationship,” says an insider. “Shania considered Marie-Anne one of her best friends.”

“This came out of left field,” the source added.

Twain and Lange have a 6-year-old son together.