I just love the press-released written apology card that some celebrities play when they are in their darkest hour.  I think Peter Cook feels his "sorry" will hold more weight if millions of people read it.  I can't speak for Christie Brinkley but that crap doesn't work for me. These matters should be kept as private as possible. Instead Peter's attorney, Norman Sheresky, released the following statement to Cindy Adams:

"I'm sorry. I'm contrite. I'm stupid. Foolish. No excuse." He adds, "I love my wife. I have loved her since the day I met her... For a lifetime, I've tried to prove how much I love her."
Meanwhile, Sheresky states, "He got involved, in over his head somehow, and he wants to make it up to her for the rest of his life. He didn't invent adultery. He didn't invent the kind of person who would engage in it with him either. He hopes there's no divorce. If she wants one... it will not be nasty. She can have whatever she wants." Cook was disgraced when news of his affair with 19-year-old Diana Bianchi went public at the beginning of the month. Bianchi, a budding singer, has since come forward to confirm the romance. (source)