The 45-year-old Oscar winner opened up to Who magazine about her struggle after the breakdown of her 10-year marriage to the Hollywood star.
"I got married really fast and really young," Nicole revealed.
"But I don't regret that because it got me [adopted children] 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."
Nicole elaborated on her personal turmoil following the highly public split.
"There were times following [the divorce] when I thought, 'Wow, this is the loneliest, loneliest existence,'" she told Who.
"But with Tom, it was a fantastic decade. I wish all of the people that have been involved in my life well, because it's very important to me to be in a place of forgiveness and love."
Nicole was 23 when she married her Days of Thunder (and later, Far and Away and Eyes Wide Shut) co-star Tom, who was 28 at the time.
In the interview, Nicole commented for the first time about Tom's recent divorce from his third wife Katie Holmes.
"I never spoke to her. I wish all of them well, but I was not involved in any of that," she said, keeping tight-lipped.
The Moulin Rouge! star was more relaxed speaking about her marriage to Keith Urban, and their daughters Faith, two, and Sunday Rose, four.
"I'm amazed that I have been a mother for so much of my life now. It's odd, but because of them I don't feel 45," Nicole revealed.
She elaborated on her struggles to conceive children while married to Tom and afterwards.
"I had tried and failed and failed. Not to be too detailed, but I've had an ectopic pregnancy, miscarriages and I've had fertility treatments," Nicole said.
"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."
Nicole described the birth of biological daughter Sunday Rose in 2008 as "the miracle of my life". Two years, Nicole and Keith welcomed Faith into the world with the help of a surrogate.
"All my kids are highlights of my life," Nicole added.
"I remember when we adopted Bella, her looking at me for the very first time. That is extremely powerful, like a kind of birth, too. They are all my biggest joys."
All of her motherly love makes her acting in upcoming horror flick Stoker all the more impressive watch her play the mother from hell in the trailer:
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