"Jessica and I began playing these parts even when we were by ourselves," he says of their roles. "It became a really blurred line. There was a question about what truly was our reality."
Lachey, 32, makes the comments to Rolling Stone in a new interview. Among the singer's more startling revelations: "I'll tell you how I knew my marriage was over: I was told."
He tells the magazine he was "blindsided" when his then-wife told him after dinner last November: "I think I want a divorce."
"I basically said, 'Please, let's sleep on it.' But when we woke up the next day, Wednesday, she was still sure," he says.
Lachey also lifts the veil on his feelings about ex-father-in-law (and Jessica's manager) Joe Simpson. "I don't pretend to understand Joe," he says. "I don't know if he ever liked me. To this day I couldn't say. It was painful. Do I think Joe drove a rift between us? No. Was he an influence in our marriage? Absolutely."
In related news, the music publication also says that singer-songwriter Adam Green has a big new hit in Germany called "Jessica," described as an unflattering ditty about Nick's ex. Its lyrics reportedly mention her "fraudulent smile" and "injections of cortisone."