Arnold Schwarzenegger celebrates birthday with ex-wife

Arnold Schwarzenegger celebrated his 68th birthday—with ex-Maria Shriver by his side.

The Terminator star was spotted arriving at the Montage hotel in Beverly Hills, Calif. on Thursday, where he was joined by his 59-year-old ex and two of their children, Katherine, 25, and Christina, 24. 

Schwarzenegger, who was dressed casually in a navy blue polo shirt and khaki slacks, was photographed exiting his fancy convertible sports car. Shriver, meanwhile, looked chic in a dark blue wrap dress teamed with a white handbag and classic sandals. 

The former governor of California and the veteran broadcaster split in 2011 after 25 years of marriage shortly after the actor confessed that he has secretly fathered a son in October 1997 with an employee, Mildred Baena. The two are also parents to sons Patrick Schwarzenegger, 21, and Chris Schwarzenegger, 17.  

Last month, the Maggie star opened up about his highly-publicized split in an interview with Howard Stern on Sirius XM and said the breakdown of his marriage was his "biggest failure." 

"I had personal setbacks, but this was without any doubt the biggest setback and the biggest failure. Without any doubt! And not only failure, but you really feel like, 'I am to blame for it. It was me that screwed up.' And you can't point the finger at anyone else," he said. "So yeah, I was disappointed, but it's always easy to be smart in hindsight. The thing was, 'How do you now make the best of that?'"

Schwarzenegger also revealed that he and Shriver sought help from a marriage counselor, although he said the process was "counterproductive." 

"It was the biggest mistake I've ever made because that guy was so full of s--t...It was absolutely, totally counterproductive to our future relationship or to any hope to get together or anything like that...Maria talked me into it. I went, and I felt instinctively maybe I shouldn't go because I know I screwed up," he explained. "I don't have to go to anyone to have him explain to me anything. I apologized to Maria. I apologized to the kids. And I tried to then move forward and say, you know, 'How do we make the best of it? How can I stay friends with Maria so we can raise the family together, even though she moves out?'" 

Schwarzenegger is not officially divorced from Shriver. His third son, Joseph Baena, is now 17 years old. 

"He is terrific and he totally understands the situation," he told Stern of Baena. "It all has worked out really well. It's a very tough situation for him. It's a very tough situation for my kids, a very tough situation for my family. It's tough for everybody." 

As for how he kept his family together? 

"The only way it happens is if all of you work together," he said. "So my wife was helpful, the kids were helpful, people around us were helpful, and so I tried to be as helpful as I can with the whole thing. I was one of the fortunate ones that we have really great, great kids."