WWW- PAT O’Brien, the host of “The Insider” who entered rehab on Sunday, has more to worry about than sexually explicit voice-mail messages. There’s a photograph, too.

An impeccable Left Coast source says that O’Brien’s girlfriend, “Betsy,” has an ex-husband who is in possession of a “compromising photograph” of the mustachioed broadcaster pleasuring himself.

“There’s also an e-mail Pat O’Brien sent to Betsy laying out the framework for [having] an affair,” said our source.

“It’s like a blueprint, something in his file that he has sent out before.”

Betsy is described as an attractive blond mother of two daughters. “She left her Pasadena husband when Pat seduced her,” said the family friend.

The ex-husband is said to be well-off financially, but he might let the photo be sold to one of the supermarket weeklies – because he doesn’t like O’Brien. “He’s finished with the divorce and he’s moved on,” said our source.

Betsy figures prominently in voice mails that were posted Monday on the Internet, in which a man who sounds like O’Brien is heard trying to coax an unidentified woman into a threesome.

“Let’s have [bleep]ing sex and drugs and just go crazy,” the voice says in one of three messages, most of which is repetitive and unprintably graphic. “You’re [bleep]ing sexy, I want to go crazy with you.”

“You are so [bleep]ing hot . . . my girlfriend is so hot, you are so [bleep]ing hot. Please leave me a voice mail, leave me a voice mail. Bye.”

In the third message, the voice says: “I am so [bleep]ing into you, but Betsy’s so [bleep]ing jealous . . . I told Betsy you’re into her and if you get this message just look at me and say yes. I want to [bleep] your [bleep] and get crazy. I don’t know why I’m like this, but you have to be with Betsy, too.”

O’Brien, who has one child with his wife, Linda, has taken Betsy out with him in public to many events over the past few months.

A spokesman for “The Insider” said O’Brien won’t be coming back to the show “until he is better.”