Jamie Lynn Spears' baby daddy a cheater

Spears' birthed her baby at 17 out-of-wedlock, and baby daddy Casey Aldridge has apparently been cheating on her for some time, according to In Touch magazine.

Kelli Dawson, a 28 year-old who is the alleged "other woman" is talking about her relationship with Jamie Lynn’s man in the tabloids.

Dawson says she met 19 year-old Casey back in November 2006 at the home of her sister.

Casey was already dating Jamie Lynn, but according to Dawson that did not matter, they had sexual chemistry.

She tells In Touch Weekly, "We were both really attracted to each other. He totally instigated it and pursued me. His friends would tell me that he liked me, that he thought I was pretty."

Well, in order to protect herself, Dawson claims they saw each other a few times and “kissed randomly.” Adding that things got “hot and heavy” later on in the Spring of 2007.

Even though Casey was still with Jamie Lynn at the time, Dawson says "You never knew if they were broken up or not, because it changed from day to day!"

Dawson says, “One morning, he called and asked me to meet him in town. I said, 'You're supposed to be on a flight right now,' and he said, 'I'm not going.' He called Jamie Lynn and told her that she would have to go by herself. She was irate. I think she knew he was staying because of me."

Dawson and Casey were even sleeping together, according to her, when Jamie Lynn announced she was carrying the baby.

Though, Dawson says, she and Casey stopped sleeping together a few months before Jamie Lynn gave birth to their daughter.

"It just didn't feel right," says Dawson. "He had to deal with the baby coming, and it had to stop."

However, things apparently stopped between Dawson and Casey because she got back together with an ex last August. She told In Touch:  “Casey was furious about that.”

Dawson claims she Casey got back together before the year ended. Adding, "It happened very casually. He came by the house and I went off with him in his car and had sex. Sometimes, we would go to his house or we would fool around in his truck, just driving around and then parking."

According to Dawson the last time she slept with Casey was in March but "even after we stopped having sex, we would still kiss occasionally."

The tabloid contends that Britney Spears’s ex-husband Jason Alexander knew about this.

Alexander says, “Kelli and Casey have been a couple on and off for a few years. They were a really tight couple, but I think it was hard for Kelli, having Jamie Lynn in the picture.”

Dawson adds she still sees Casey: "I see him all the time, at least once a week.”