"We're honest with each other," the actor tells PEOPLE. "We're respectful, and that's what it comes down to"
Following Cox’s confession on The Ellen DeGeneres show last week – “He’s my best friend in the world,” she said, “I love him” – Arquette, 41, says the feeling is mutual.
“She’s incredible,” he told PEOPLE Saturday at the Art of Elysium Sixth Annual Heaven Gala in L.A., where he was honored and was accompanied by girlfriend Christina McLarty. “I love her, too, and she’s an amazing person, a beautiful person.”
What’s their secret to keeping things amicable?
“We have a great relationship because we treat each other with respect,” he says. “We’re honest with each other. We’re respectful, and that’s what it comes down to.”
Cox, 48, and Arquette, who have an 8-year-old daughter, Coco, both filed for divorce last June, citing irreconcilable differences. They announced their separation after 11 years of marriage in 2010.
• Reporting by REAGAN ALEXANDER