It wasn't the $2 million he allegedly asked for that prompted Joe Halderman to allegedly blackmail David Letterman – it was jealousy, according to a source.
In August, Halderman, 51, caught the talk-show host and his then-girlfriend and Letterman's onetime assistant Stephanie Birkitt passionately kissing while in a car in the driveway of the Norwalk, Conn., home Halderman shared with her, a source tells PEOPLE.
Letterman and Birkitt "were seen making out in the driveway in August," the source says. "He drove her home once a week. The interesting thing was he lives in North Salem. Driving her home to Norwalk wasn't exactly the next town."
The PEOPLE source did not confirm a report in the New York Post that Birkitt agreed to end her relationship with Letterman after being caught in flagrante delicto, but did say that "by that time [Halderman] knew she had a sexual relationship with him but was going to stop it."
Shortly after being discovered with Letterman, Birkitt and Halderman broke up, and she moved to Manhattan.
Previous reports had suggested that Letterman, 62, had broken off his relationship with Birkitt, 34, before the birth of his son in 2003. He married his longtime girlfriend, Regina Lasko, in March 2009, and publicly apologized to her on the air after breaking the news of the alleged extortion scheme.
The source would not confirm how recently Letterman and Birkitt had been together romantically.
Shout-out to my fellow Fairfield County CT ONTDers