Say it ain’t so, David Letterman…

David Letterman and the 2005 Emmy Awards (Vince Bucci/Getty)

In the so-called “late night” wars, it turns out David Letterman’s worst enemy is himself. The Lenos and Conans, the Arsenios and Chases, the Magics and Kimmels — they all come and go, but in the end, Dave is stuck with the one competitor he can’t ever vanquish…

And so far, his audience has always forgiven him… but his latest self-imposed obstacle will be his audience’s biggest hurdle yet.

Thursday, in what should have been a celebratory week for the host of CBS’ “Late Show,” (more on that in a bit), Letterman instead announced to his studio audience that he’s been the victim of an extortion plot by a man who threatened to expose multiple affairs Letterman had had with “Late Show” staff members. He said he cooperated with the Manhattan District Attorney and the man has been arrested. Oh… and the rumored affairs? All true, he admitted.

What other sordid things has David Letterman been up to? Write your own punchline for David Letterman’s Top 10 Stupid Human Tricks.

I know they say comedians are, as a stereotypical rule, self-critical, self-defeating types, but David Letterman takes it to new heights. The extortion is criminal, to be sure, but let’s be honest here: there’s only so much sympathy to go around for a married man who got caught in someone else’s bed. Was Dave the victim of a crime? Yes. Was it his own misdeeds and hubris that put him the situation that made that crime possible? Yes.

Letterman should be riding high these days. His ratings are better than they’ve ever been — he’s regularly beating “The Tonight Show” in total viewers; last week, for the first time since we were in short pants, he beat “Tonight” in the 18 to 49 demographic. And his also-ran underdog status — the unspoken weight around his ankle since NBC passed him over for “The Tonight Show” in 1992 — seemed to finally be dissipating, along with the surly reputation that’s dogged him for decades. Glowing magazine profiles declared that, at age 62, he’d finally grown up. Fatherhood seemed to mellow him. He married his longtime girlfriend earlier this year. His show, while still reveling in the absurdist humor that he trademarked 25 years ago, was growing more pointed and personal, as he began to drop the “too hip for the room” attitude and let audiences laugh — or get pissed — with him.

There has always been a subset of Americans who love and root and stick with Letterman and his TV show though he often doesn’t make it easy. They loved him when he was host of “Late Night” and was inventing a secret club of wise-ass-television after all the grown ups had gone to bed. They stuck with him when his guests called him an asshole. They stuck with him when he refused to go along to get along and NBC, unsurprisingly, picked safety over prickly talent and gave “Tonight” to Jay Leno. And they stuck with Dave when he had to suffer the indignity of following the very show we all knew he should have been hosting.

Dave moved to CBS, and that audience came with him. It cheered him on when his former friend, Leno, sold his comedy soul for ratings gold. They stuck with Dave when he disappeared from the air for weeks and months — first with heart surgery and later shingles. They welcomed him back when he tanked as host of the Oscars. And when, earlier this year, Sarah Palin tried to gin up a phony controversy about Dave’s jokes, the Letterman faithful stood by their man even as he issued a sort-of apology.

Now Dave has given his fans their biggest test. Will they continue to root for a man who was forced to admit to multiple affairs?

Update: There’s still question about when the affairs happened — was it before Letterman and longtime girlfriend Regina Lasko had a child together? Before they got married? Does that matter in how you react to the news? Is it OK to cheat on your 20-year girlfriend with women who work for you, but not on your wife?

Johnny Carson turned the indignity of his very public divorces into disarming, self-deprecating comedy. But this is too hard to spin. True, we’re less shocked than we were 30 years ago when we learn about the dirty laundry of our celebrity’s private lives. But joking about paying alimony and joking about how you were plowing the girls at work while your wife and son were at home is a different kettle of fish. In the video above, the audience laughs, but you can’t miss the audible gasps when Dave first utters the words. And after the news sinks in, will audiences look at him differently? I know I will… at least for a little while.

Still, he’s funnier than Leno…

Update: Now, with a night to digest the news, I’d like to add this:
Initially, Dave will get a ratings boost from the rubber-neckers who want to see how he jokes about it. But because 1. Dave has always been tight-lipped about his personal life (his own staff didn’t know he got married until he mentioned it on the air) and 2. It’s pretty unseemly to sleep with your staff and then joke about it on the air and 3. It’s an ongoing legal matter — I can’t imagine he’ll have much of anything to say about it on the air. Which means people will stop being intrigued by it b/c he’s not feeding the obsession and his ratings will come back to where they are now (which is still very good).

And eventually, American’s will forget and move on. They say Americans are forgiving — but I think it’s less that and more that we have short attention spans; we’ll find something else more sordid to obsess over and just move on to gossip about that.