The Oscar-winning actress married her Days of Thunder co-star in 1990, when she was just 23, and they adopted two children together before Cruise moved to end their 10-year union in 2001, citing irreconcilable differences.
Kidman reveals she was especially devastated by their split because she didn't see it coming.
She tells DuJour magazine, ""I was totally smitten. I fell madly, passionately in love. I was reeling with Tom. I would have gone to the ends of the earth for him. We were in a bubble, just the two of us. We became very dependent on one another...
""(I thought) our life together was perfect. It took me a very long time to heal. It was a shock to my system.""
And the 45 year old admits the hardest part was losing her best friend: ""I realised I didn't want to be alone. I wanted to fall in love again, but I wasn't sure I could.""
Kidman eventually met and married country star Keith Urban in 2006, and the actress insists she couldn't be happier, adding, ""My life changed. He is a wonderful, caring man and he makes me feel secure. We don't ever like to be separated.""