"Matt cut himself off from the life he knew in Manhattan and has remained for the most part isolated," the source tells ET. "He looks exhausted. Matt is finally coming to terms with the reality that his marriage is over and he is in bad shape. He feels he lost everything important in his life overnight. He is embarrassed and ashamed."
"There is no chance at this point they will work things out," the source adds of his relationship with Roque. "Matt held on to the idea that Annette might eventually forgive him because she had always stuck by him but now he has no hope."
According to the source, Roque has already met with attorneys and the divorce proceedings are moving forward. The two share three children together -- Jack, 16, Romy, 14, and Thijs, 11.
"They are settling all the details," the source says. "Annette's friends don't feel [the split] was overnight. It has been building for years. The truth has finally surfaced. They barely ever speak to each other anymore and only recently tried to constructively discuss the divorce settlement."
The source says the former couple talked two weeks ago to try to negotiate some of the details on their own.
"Annette is angry," the source says. "She feels Matt's behavior has affected a lot of people and has embarrassed the whole family."
"Annette plans to receive a very good settlement in this divorce," the source also claims. "She wants to make sure she and the children will always be well taken care of."
As for Lauer, the source says he is remorseful.
"Matt feels terrible and regrets his behavior but his regret isn't enough right now," the source says. "It feels like all doors have closed for him."
Earlier this month, ET spoke to Lauer's former Today show co-workers, Savannah Guthrie and Hoda Kotb, at The Hollywood Reporter’s 35 Most Powerful People in Media Celebration, where they shared that the newsman's top priority is currently his family. Both Guthrie and Kotb are still in touch with Lauer.
“I just know that he's really focused on his family right now and I think that's right," Guthrie said.
“Yeah, I think that is really where his heart is at this moment -- his children and just working on that," Kotb added. "So, I think that work probably isn't in the forefront of his mind.”