Christie Brinkley's Divorce Battle: It's Ugly!

Christie Brinkley and Peter Cook's messy divorce battle officially made its way into the courtroom today, and Peter wasted no time spilling juicy details about his affair with an 18-year-old and love of porn.

Christy's fourth husband admitted to sleeping with Diana Bianchi on 12 separate occasions, including twice in his office and five times at each of his homes. The affair began in March 2005 — eight years after he married the model. Peter also admitted to buying expensive gifts for the teen and hiding them around the office for her to find.

Peter, who admitted he hired the teen to seduce her, read an email he sent to Diana during their affair: "I don't know, you put me under your spell," the e-mail began. "You never asked me, but I left you money anyway."

That wasn't the worst of it. Peter testified to pleasuring himself in front of strangers over a Web cam, seeking out "young fit girls" from an online swinger Web site and indulging in other forms of online porn.

He testified about his adoptive son Jack, now 13, stumbling upon his nudie pics on the computer.

"He said, 'Mom is looking at naked pictures of your girlfriends on the computer," Peter said as he cried on the witness stand.

Not all of the bad mouthing was directed at Peter, though. Christie's history with men was called into question by Peter's attorney.

"For goodness sake, she's on her fourth husband," Norman Sheresky said. "Your honor, we're here because of the self-indulgent wrath of a woman scorned.... What kind of a mother wants her husband flogged in public?"

More than 60 witnesses are expected to testify during the rest of the proceedings, which are predicted to continue for at least month.