Christie Brinkley Files for Divorce THURSDAY SEPTEMBER 14, 2006 12:25PM EST THURSDAY SEPTEMBER 14, 2006 01:25PM EST UPDATED By Stephen M. Silverman and Sharon Cotliar Brinkley and Cook in 2003 Photo by: ANDREA RENAULT / GLOBE Christie Brinkley is officially ending her fourth marriage, to architect Peter Cook. Cook's attorney, Norman Sheresky, has confirmed to PEOPLE that his client has now been served with a summons, which is the first step in moving forward with a divorce. "The next step would be for (Brinkley) to serve a complaint and/or for the parties to negotiate an amicable agreement," Sheresky tells PEOPLE in an e-mail message. Sheresky's business partner, David Aronson, tells PEOPLE 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," says Aronson. "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." Asked if Cook hoped to reconcile, Aronson says, "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 and Cook announced they were separating after 10 years of marriage. "(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," the CoverGirl model's representative, Elliot Mintz, said at the time. Brinkley, 52, was previously married to artist Jean-François Allaux (1973-81), singer Billy Joel (1985-94) and developer Richard Taubman (1994-95). She and Cook, 47, who lived in New York's tony Hamptons region, have a daughter, Sailor, 8. She and Joel have a 20-year-old daughter, Alexa, and she and Taubman have an 11-year-old son, Jack, whom Cook adopted after he and Brinkley wed in 1996. The breaking point in the marriage was Cook's relationship 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 confronted about it by Bianchi's stepdad, Southampton Village police officer Brian Platt, PEOPLE reported. In July, 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's attorney, Eleanor Alter, and Elliot Mintz both declined to comment on the divorce filing.