Stephanie Birkitt

David Letterman outside the Ed Sullivan Theater in New York (8/27)

I hope David Letterman's super secret sex lover wasn't hoping for a promotion. She's pretty much been fired. From TMZ:

TMZ has learned Stephanie Birkitt -- the woman at the center of the David Letterman sex scandal -- has been banned from setting foot on the CBS set where the "Late Show" is filmed.

Birkitt used to be David's assistant -- appearing on the "Late Show" numerous times -- and later became his personal attorney. It was Birkitt's ex-boyfriend -- Robert Halderman -- who discovered Letterman's secret relationship with her ... and then allegedly threatened to release the scandalous information unless Letterman forked over $2 million.

Sources tell TMZ that security at CBS is well aware of Birkitt's ban from the set.

Worldwide Pants just issued the following statement: "Stephanie is on paid leave of absence ... she has not been banned from the Ed Sullivan Theatre."

But TMZ just spoke with someone associated with security at Letterman who just told us, "Security got a verbal order that she is 'banned' from the property for the time being."

What an ungrateful asshole. If David Letterman's going to have sex with one of his subordinates at the office, the least he can do is let her come by and pick up her work belongings (e.g. her files, pencils, and soiled underwear). Knowing that she's being forced to stay away after being used for sex must be devastating for Stephanie . . . especially since that sort of degrading treatment by guys is usually reserved for prostitutes. Or Pam Anderson.

David Letterman on vacation in St. Bart's (12/2008)

David Letterman admitted on last night's show that he was the victim of an extortion plot. Robert "Joe" Halderman -- a "well respected" producer for 48 hours (PIC HERE) -- threatened to go public with evidence Dave had had an affair with "more than one" Late Show staffer, unless he was paid $2 million. Dave has been dating Regina Lasko since 1986; they married earlier this March. From Variety:

Letterman told his audience on Thursday that he contacted the Manhattan District Attorney's Special Prosecution Bureau. That led to a sting operation, in which Letterman met with the individual and handed the person a fake $2 million check. That person was arrested on Thursday.

"This morning, I did something I've never done in my life," Letterman said on Thursday's edition of CBS' "Late Show." "I had to go downtown and testify before a grand jury."

As part of the testimony, Letterman admitted that he had engaged in sexual relationships with staff members.

"My response to that is, yes I have. Would it be embarrassing if it were made public?  Perhaps it would," Letterman said.  "I feel like I need to protect these people -- I need to certainly protect my family."

According to a warrant obtained by Fox 5 New York, one of the women Dave allegedly had an affair was his former assistant Stephanie Birkitt (PIC HERE):

And, the warrant says, Birkitt was the suspect's girlfriend and we've learned she was living with him until recently.

According to the warrant, the suspect, "48 Hours" producer Robert "Joe" Halderman, sent Letterman a package which allegedly included treatments for a screenplay with supporting materials.

The warrant goes on to say the "supporting materials" included copies of parts of a diary and correspondence belonging to Birkitt.

This is just horrible of Dave, using his position of power and authority to seduce women. Compare his situation with Jimmy Fallon's. Jimmy actually has to convince women he's not "that guy who hosts Late Night" in order to get them to sleep with him.