Christie Brinkley Will Divorce Cheating Husband

As expected, Christie Brinkley is officially ending her marriage to Peter Cook, the Eastern Long Island architect who cheated on her with his teen assistant earlier this year.

Cook's attorney, Norman Sheresky, has confirmed that his client has now been served with a summons, the first step in divorce proceedings.

"The next step would be for [Brinkley] to serve a complaint and/or for the parties to negotiate an amicable agreement," Sheresky told People in an e-mail.

Sheresky's partner, David Aronson, reports that Cook is distraught over Brinkley's decision to go ahead with a divorce.

"He was hopeful that they would be able to work through this and continue their marriage. He is saddened by the fact that she has decided to move forward, but he understands that's her right and he will respect that," Aronson said.

Asked if Cook hoped to reconcile, Aronson said: "Absolutely. He made no bones about that to her and the few times he's spoken to the press. He hoped they would work through their problems and continue with their life together. He loves his children and family."

On July 11, Brinkley, 52, announced she was separating from Cook, her husband of more than 10 years. She and Cook, 47, who lived in New York's posh Hamptons region, have a daughter, Sailor, 8. Her 11-year-old son, Jack, was adopted by Cook after he and Brinkley wed in 1996.

Christie and ex-husband Billy Joel have a 20-year-old daughter, Alexa Ray Joel, who is starting to launch her own music career.

"(Christie's) immediate concern is for her children, and she's hoping during this obviously difficult time that people will be kind enough to respect her privacy," Brinkley's rep said.

The breaking point in the marriage was not hard to pinpoint -- Cook had an affair with Diana Bianchi, an 18-year-old he'd hired to work in his firm.

The affair first came to Brinkley's attention on June 25, when she was told about it by Bianchi's stepdad, Southampton, N.Y., police officer Brian Platt.

Cook attempted a public reconciliation, telling New York Post columnist Cindy Adams through attorney Sheresky, "I love my wife. I have loved her since the day I met her. Please. I love her. For a lifetime, I've tried to prove how much I love her. This is an aberration. I'm sorry. I'm contrite. I'm stupid. Foolish. No excuse."

Brinkley declined to comment on the divorce.