(Cover) - EN Showbiz - Shania Twain blames her best friend for having an affair with her then-husband, calling her "deliberate and calculating".

The country musician and her ex-husband Robert John Mutt' Lange separated after he became involved with her close pal, Marie-Anne Thiebaud. Shania is now happily married to Marie-Anne's ex-spouse Frederic Thiebaud, but the betrayal left its mark on her.

She admits blaming Marie-Anne more than Robert, adding that's something she's always been open about with Frederic.

"The fact that my friend betrayed me was a shock, I didn't see it coming. You feel really stupid when someone takes advantage of you. For a while after something like that you feel like a total idiot, you're asking yourself every day, How could I not see this coming?'" she explained to ET.

"I've had a different anger towards her than I had with Mutt. I just felt that my friend's perspective was more deliberate and calculating."

Shania and Frederic had always been good friends and he was the first to admit when his feelings started to become romantic. She didn't feel ready to enter another romance at that time as she'd been left so devastated by the end of her marriage.

The 45-year-old even told Frederic not to wait for her as she'd never open her heart to another man, but eventually she did.

"You can't prevent those things from happening," she mused.

"Fred certainly was the first to admit it. He said to me, You don't have to love me back, I'm not asking that, just let me love you.'"

The pair tied the knot in Puerto Rico in January and it's a day which meant a great deal to Shania. Kissing her new husband for the first time felt like the beginning of a new life and is something she will never forget.

"It was as though I was walking on a bridge between then and now," she said, of walking down the aisle. (C) Cover Media