Jana Kramer's estranged husband is offering the singer and actor a public apology after she says he was unfaithful during their 15-month marriage.

Kramer separated from Michael Caussin, a former NFL player, in August, and though she was mum about her reasons at the time, a report came out from Us Weekly alleging that Caussin was repeatedly unfaithful during their time together, even seeing a paid escort. The report also claims that he has entered rehab for sex addiction. Now Kramer -- who had two previous marriages -- tells People that his betrayal hurt the worst of any she's experienced.

"Mike was the biggest of the betrayals because it was the first time in a relationship where I truly loved the version of me. I didn’t feel I had to prove that I was good enough, I was vulnerable and finally at peace with myself," she says. "But I was fooled."

Neither Kramer nor Caussin have directly confirmed that he is in rehab for sex addiction, but Caussin tells People, "I acknowledge that certain actions and behaviors have caused issues in my marriage and I am deeply sorry for the pain I have caused Jana ... I have and will continue to take the steps needed to change who I am as a person in order to be a better husband and father."

Kramer recently revealed first husband, Michael Gambino, was so abusive that he went to prison for trying to kill her. Her second marriage, to actor Jonathan Schaech, was very short-lived, and she says a distant relationship with her own father as a child has colored her choices as an adult.

"Nothing was ever good enough for my father," she shares. "I was always trying to get his attention and, through therapy, I realized that followed through into my relationships."

But now, Kramer feels she's really ready to move in a different direction.

"I am truly starting to figure out my worth," she tells People. "My main problem, which is one reason why I’ve been in bad relationships, is that a family is all I want. It’s all I’ve dreamed of. I wanted to be loved and I wanted to love someone."

Kramer and Caussin welcomed a daughter, Jolie Rae, in January. Kramer is currently competing on Season 23 of Dancing With the Stars, balancing  the tough schedule against her singing career and being a newly-single mother.

“I’m trying to manage it the best that I can and show single moms out there that we can do it,” she says. “We can do it all, hear us roar.”

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