Catherine Zeta Jones' tribute

Catherine Zeta-Jones paid tribute to her 'best friend' Michael Douglas as they celebrated their 17th wedding anniversary.

The Mask of Zorro star took to Instagram to post a sweet message for the Hollywood star, 73, as they celebrated 17 years of married bliss, admitting that she never thought their life would be as good as it is right now.

Alongside a picture of the pair on their wedding day, Catherine wrote on Instagram: '17 years ago today, I said 'I do' to my best friend and father of our two and a half-month-old son. 

'Thought it could never get better than that day, but it did. Happy anniversary darling, Michael. With you, in my life, and Dylan and Carys, every day could be a twelve-hour fantastic party at the Plaza in New York. Love you. #love #lovestrong'

It comes after Catherine revealed the key to the couple's long and successful marriage is that they listen to one another. 

After overcoming Michael's battle with cancer and her own battle with bipolar disorder, the brunette star says they are in a better place than ever.

The 48-year-old actress - who has Dylan, 17, and Carys, 14, with Michael - added: 'I'm very blessed. I have a husband who listens to me and I'm a wife who listens to him.

'That's why - although every marriage goes through its ups and downs, its times of adversity - we've come to a place where we couldn't be better. 

'I have a very healthy husband, a very healthy mother and two vivacious, healthy children. I think after that, everything just falls into place.' 

This article was first published on dailymail.co.uk and is republished here with permission.