"Pregnant man" Thomas Beatie was arrested Thursday by Phoenix police for allegedly placing a GPS tracking device on his estranged wife's car to stalk her.

"The first feelings were fear, that he's been doing this to me for so long," Nancy Beatie, Thomas' wife, told 3TV. "Then a little bit of not feeling well, like sick. Like, oh my gosh, he's been knowing everywhere I've been, stalking me, and it's scary."

According to court documents, Thomas admitted to implanting the device on his wife's car years ago so that he could log onto an online account and monitor her movements.

TMZ reports that Beatie has been charged with felony stalking and is incarcerated at Phoenix, Arizona's famous Tent City jail where prisoners are housed in tents, dressed in chain-gang stripes, and male prisoners are forced to don pink underwear.

3TV received an email from Amber Beatie, who claims to be Thomas' fiancée.

"The only reason for Thomas using the GPS was to give us peace of mind when the children were with Nancy," the email reportedly said in part. "... in no way did he believe he was doing anything illegal by wanting to protect his children and ensure that they were not taken from him or in danger in any way."

The email also claimed that "Nancy has never been a truthful person"

"Nancy] has made many threats in regards to disappearing with them, this was the only solution he could come up with at the time," the email continued.

Amber is confident the felony stalking charge will be dropped.

Nancy has denied claims that she has threatened to take the children. She wants to co-parent amicably, she said.

"She's just tired of being bullied, being harassed and now stalked by him," David Higgins, Nancy's attorney, said. "Hopefully, this puts an end to it."

Thomas is not expected to remain in the Tent City jail long and will most likely be given probation, according to authorities.

A transgender man with female reproductive organs, Thomas had gender reassignment surgery in 2002. He later married, and after learning that his wife was infertile, became pregnant through artificial insemination. It was then that he made headlines as a "pregnant man." Over the next few years, Thomas gave birth to the couple's three children.

The couple filed for divorce in 2012, but the divorce is pending.