The 45-year-old actress - who adopted two children with the actor before they parted ways in 2001 - blamed getting married at the young age of 23 for her depression following the couple's divorce. However, she said that she has no regrets about their relationship.
Kidman told Who magazine: "I got married really fast and really young. But I don't regret that because it got me Bella and Connor, and I did have a fantastic marriage for a long period.
"Then when it didn't work out, I had to really dig deep and find my way through depression. I have no regrets about all of it. It was all part of growing up."
The Paperboy star is now happily married to country singer and American Idol judge Keith Urban. The couple are parents to 4-year-old Sunday Rose and 22-month-old Faith, who was born via surrogate.
Kidman admitted that being unable to conceive naturally had a huge impact on her depression, and she was left devastated by a series of miscarriages and failed IVF treatments.
"I had so much time thinking that wasn't going to happen in my life and trying to understand that," she recalled. "When it did happen - and for it to be a surprise - that was great.
"I had tried and failed and failed and failed. Not to be too detailed, but I've had an ectopic pregnancy, miscarriages and I've had fertility treatments. I've done all the stuff you can possibly do to try get pregnant.
"Every woman who has been through all those ups and downs knows the depression that comes with it. So the way it just happened with Sunday was like, 'What?' The percentages were so low. It is the miracle in my life."