The Australian actress fell for the Top Gun star after they met on the set of their 1989 movie Days of Thunder, but admits she was unprepared for the scrutiny the couple faced.
She tells Harper's Bazaar magazine, "In those early years, it was like, 'I'm here and I'm clutching onto your arm, and it all feels a little overwhelming and really strange.' And I was shy. Deeply shy. I didn't feel comfortable at all. But I felt very comfortable at home."
Kidman split from Cruise in 2001 and went on to find love with second husband Keith Urban, who she credits with helping her feel secure.
She adds, "He just gave me confidence. Through just being very kind to me and understanding me, opening me up to trying things, my sexuality, those sorts of things... (He has) a bigger, stronger personality; that's what I've been drawn to. I need protection. Everyone wants to feel someone's got their back."