Jesse James "never really trusted" his ex-wife Sandra Bullock and refused to believe she truly loved him.
The couple wed in 2005 but its union was rocked last March when James' infidelity was exposed in a U.S. tabloid, just days after Bullock won an Oscar for her role in The Blind Side.
Their divorce was finalized months later and now the TV mechanic has confessed he was always insecure about the relationship.
In his upcoming autobiography, American Outlaw, James writes, "I never really trusted Sandy. But no matter how many times she told me, it just didn't take. I nodded when she said she loved me. Inside, I was always thinking to myself, 'Sure. We'll see'."
"I screwed around behind Sandy's back and the whole world came to know about it. I can't go back and I can't save my marriage."