The 38-year-old actress split from the 'Magic Mike' star in April 2018 after almost eight years of marriage and though they came to a "slow realisation" they wanted different things from life, rather than one event causing the breakdown of their relationship, she found the aftermath "so difficult".
She said: "I always say no one gets married to hopefully get divorced.
"People grow and they change and sometimes they don't grow and change together. So it wasn't a overnight thing that happened. There was no one event. I think it was just a slow realisation that we wanted different things.
"I was just gutted. It was so difficult for me. It was the loss of an idealistic future for myself and my life. What does that now look like for me? Where do I begin? I met him when I was 24, I didn't know life without Chan."
The 'Step Up' star and her ex-husband - who have six-year-old daughter Everly together - are still "getting used" to life apart and don't want to dismiss the bond they used to have.
She said: "We're all aware that it's a new normal, we're all getting used to it. You can still have a relationship and just because the forms change as to who you are to each other, it doesn't take away from the love that we had or that we shared all those years."
Jenna has now found love again with Steve Kazee and they are expecting their first child together and the 'Flirty Dancing' star is delighted to be so happy after such a difficult time in her life.
She told People magazine: "It was a hard journey of growth and change. Ultimately now I can honestly say that I'm living in a very joyful new place in my life, and I'm happy about it."