Kramer, 37, announced the breakup with a message on Instagram on Wednesday.
"As I try to make sense of a reality I never wanted to believe could be possible again, those words have now become a reality. I've fought y'all. I've loved hard. I've forgiven. I've put the work in. I've given everything I have, and now I have nothing else to give. 'It's time,'" she wrote.
"Please know that I still believe whole heartedly in marriage, love, and rebuilding. I just can't fight any longer.It's time to heal. Thank you for all the love, heart, and support, in many ways you have fought on this journey alongside me, and for that I am grateful."
Her message ended with, "I'll always encourage you to continue the good fight, but you can't fight it alone."
The couple shares children Jolie Rae, 5, and Jace Joseph, 2.
In September 2020, the "I Got the Boy" singer revealed on the "Whine Down with Jana Kramer and Michael Caussin" podcast that Caussin filed for divorce in 2016, per People. She said he tried to separate when she was a contestant on "Dancing With the Stars" and while he was in rehab to help treat his sex addiction.
Kramer read an excerpt from her 2020 book, "The Good Fight," which explained, "Mike was in rehab and I was in an all-out war with my emotions. Most days, I would push Mike out of my brain and tried to live in the world as if he didn't exist. Other days I was too weak to push and I missed him, and I hoped he would be in the audience watching me perform, rooting for me."
She continued, "Regardless of how I was feeling, whenever he would call me from rehab, I would lash out at him and tell him I didn't want anything to do with him. I would hang up and realize that I had no idea what direction my life was headed in or what I should do. They only times that gave me calm was when I looked at our baby girl. I knew that regardless of the outcome, I wanted the best for her."
The "One Tree Hill" actress said that she decided to reconcile five years ago, after "a voice in my head finally spoke up in defense of this man and our marriage."
As she read from her book, "I knew what I wanted... I said to him, 'I want to try.'"
She was previously married to Michael Gambino and Johnathon Schaech.