Kevin Federline‘s ex Shar Jackson opened up about the former backup dancer cheating on her with Britney Spears.

In her memoir The Woman in Me, Britney wrote that she was unaware that Kevin was expecting a child and engaged to Shar when they met. At that point, he was already a dad to daughter Kori, his first child with Shar.

“I was clueless,” Britney recalled, adding, “I had no idea until after we’d been together for a while and someone told me, ‘You know he has a new baby, right?’”

Shar looked back on the situation in a new interview, and she shared some additional insight.

Read more about Kevin Federline’s relationship with Shar Jackson…

Speaking to the Daily Mail, Shar said that Kevin left her to go on what he described as an audition for a Coke commercial when she was six months pregnant.

“Then I didn’t hear from him for three days,” she told the outlet. “I later found out they had met at a club on the first night, when he went out with his friends. I felt angry and betrayed and I went numb. I went onto autopilot.”

She continued, saying, “I felt betrayed and crushed. I thought, ‘How could you do something like that?”

“For about a day-and-a-half I was in a state of disbelief,” she said about her response to photos emerging of Kevin and Britney together.

Shar noted that Britney was aware of her pregnancy by the time she welcomed her son Kaleb. In fact, she said that she sat outside the hospital while Kevin was in the delivery room.

The actress noted that her initial response to finding out that Kevin was cheating was not about Britney.

“I met Britney way before Kevin got with her,” she added. “We ran in the same circles and I was good friends with the guys from NSYNC [Timberlake's boy band]. I thought she was cute and adorable. I wouldn’t say Britney and I ever became close but we were always respectful and cordial to each other.”

Britney‘s relationship with Kevin ended in divorce after they had two children – sons Sean Preston and Jayden James. Shar was not surprised.

“I think her relationship with Kevin was a fantasy for both of them,” she said. “To me, anything built on a rocky foundation isn’t going to last and they started rocky because he was in a relationship.”

Britney dropped some additional bombshells about her time with Kevin in her memoir.