NASHVILLE, Tenn. -- A former girlfriend is speaking out about the way an accused serial rapist treated her during and after an intimate relationship.

Video: Former Girlfriend Explains Relationship With Accused Rapist

Robert Jason Burdick is a suspect in at least 13 rapes in Davidson, Wilson and Williamson counties. He was arrested on May 1 and is accused of raping the women from 1994 until 2008.

Burdick’s ex-girlfriend, who asked that her identity remain hidden, said she was friends with Burdick in high school about 20 years ago.

She said during what Burdick called "the rape game," he wanted her to fight him off as if it were real while she played a rape victim.

"Basically there wasn't anyone who ever really told him no, because he was very charismatic and he was very personable," she said.

She said Burdick, 38, was popular, was captain of the football team and that he was a ladies man.

"He had lots and lots of female friends. All of the girls were crushing on him," she said.

She said one of their meetings turned physical.

"The whole time that he was doing it, I was saying, 'This isn't a good idea. I don't want to be here. I don't want to do this, please stop.' And he just didn't," she said. "It wasn't a violent thing. It was just, I said 'No,' and he persisted."

She said that for years she's considered their encounter a date rape but never reported it because she thought it was somehow her fault for being at the wrong place at the wrong time.

She said another incident now has her even more concerned. She said one day while her parents were away, he came to her house and asked her to fight him off.

"He was overpowering me, holding me down, taking my clothes off with me totally struggling, crossing my legs, trying to keep him off of me, and it just didn't work. Nothing worked," she said.

She said the entire time Burdick was laughing and practically begging her to keep fighting.

"He kept saying, 'See if you can fight harder. See if you can keep me away from you.' And I fought hard," she said.

"He was role playing a rape with me, yes," she said.

Police said Burdick's first known attack was in 1994, but his one-time high school girlfriend said she can't help but wonder just how many more victims may be out there.

"If he wasn't actually doing it back then, he was definitely in progress of fantasizing about it and trying to make that culminate into reality," she said.

So far, Burdick has met with attorneys, his mother and the woman who was in the car with him when he was pulled over and arrested.

It is not clear what he said to them or if he said anything about the allegations.

Last week law enforcement officials predicted there might be others that have not been reported.

Police said that anyone who believes they may have been a victim of Burdick should call their local police.

Burdick Charged In Two More Attacks

On Tuesday, Burdick was officially charged with two more attacks in 2006 and 2007.

Police said Burdick raped a woman on Fairbrook Drive in 2007 and a woman on Otter Creek Drive in 2006.