The Australian actress, who lost her father, Dr Anthony Kidman, in September, married the country singer in 2006 after the collapse of her marriage to Tom Cruise.
She said: "I think, as anyone knows, you need a partner who is there for you through the tough times, as well as the good times.
"I think when it's really, really tough and things get hard - and recently, I lost my father - and my husband was extraordinary through that. So I'm very, very fortunate. But I spent a long time looking for him."
The actress, who is in China to play at the Mission Hills World Celebrity Pro-Am golf tournament, has been picking up tips from fellow Australian Greg Norman who gave her a six out of 10 for her game.
He said: "I gave her a six only because she's just starting to learn how to play the game.
"We as players know how to play so actually when you see somebody who wants to play and learn the game of golf, we like that.
That's why I give her a six because she's going to be very, very good."
Among the other stars at the event are actors Morgan Freeman and Jessica Alba and golfers Paul McGinley, Justin Rose and Darren Clarke. Kidman will partner Ian Poulter when the tournament starts tomorrow.
