Well, things are getting stickier in David

Letterman‘s public sex scandal.

And he may have some more 'splainin' to do.

According to her diary, "Late Show" staffer

Stephanie Birkitt was still having sex with her boss when she was living with her

CBS-producer boyfriend Joe Halderman.

This is sourced to the New York Post, which reports she left her Joe home in Connecticut when she and Letterman went on

hikes last fall at his eastern Montana ranch.

But she continued to tell Joe that she and Letterman had a platonic relationship and she was his "best friend."


Halderman exploded when he read Birkitt's diary in December, the Post's sources said.

We have a feeling there will be even more sordid details to emerge.

According to our New York sources, Letterman’s longtime affairs with staffers were common knowledge in the TV and media world.

Makes you feel a bit sorry for Joe Halderman, doesn’t it?

Nothing like being cuckolded by a rich and famous celebrity to get your dander up. We're not saying extortion is the way to go.

But we can certainly understand his anger. Can you?

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Photo: Dariya Fadeeva and Joe Halderman at the premiere of "Three Days in September." Credit: WireImage.