Revenge

Follow this bouncing ball...

Shania Twain was cheated on by her husband, Robert "Mutt" Lange.
Mutt was banging around with a woman named Marie-Anne.
Marie-Anne was a longtime friend of Shania.
Marie-Anne was married to a dude named Frederic Thiebaud.

Where does the revenge come into play?

Shania is now marrying the husband or Marie-Anne, Frederic Thiebaud.

KFed thinks they just wife-swapped.