The 43-year-old actress discussed the 37-year-old Good Charlotte guitarist on Tuesday's episode of Radio Andy with Andy Cohen. Diaz described how she and Madden first met and also gushed about their connection.
"It was one of those things where everybody tells you, 'You just know when you know,'" Diaz said. "The first thing I said when I first met my husband was, 'He's hot!' ... We had just never been in the same circle."
"I knew Nicole [Richie] and [Benji's brother] Joel [Madden] for a couple years before I met Benj," she said. "It was at my house, they were over for a barbecue and Joel said, 'Can my brother come over?' And I said, 'Of course.' Then [Benji] walked in the door and I was like, 'You!'"
Diaz and Madden were engaged less than two months before they married in January 2015. The actress previously dated singer Justin Timberlake and New York Yankees star Alex Rodriguez, but said her past is immaterial with Madden in her life.
"Nothing matters now that I have my husband," she said. "I don't even remember any of that. That's why I know he's my husband, is because no one compares. Everything else just kind of like washes and slips away."
"You realize like, 'Oh, this is like the real thing is. This is what real love is. This is what real commitment and devotion is. This is the person you build you life with,'" she said. "And for me, it's like the rest of everything dissolves."
Diaz appeared on the radio show to promote her new book, The Longevity Book: The Science of Aging, the Biology of Strength, and the Privilege of Time. The actress dedicated the book to Madden, writing, "I never knew what love was until I found you."