The pair was Hollywood's odd couple when they got wed in 2000 shortly after meeting on the set of their movie Pushing Tin a year earlier (99).
They courted controversy with their public displays of affection on the red carpet and by wearing vials containing each other's blood around their neck.
Thornton and Jolie split in 2002, and the actor cites his own insecurities over dating the renowned beauty as the reason he "blew" the marriage.
He tells America's Nightline show, "I blew it because I didn't think I was good enough for her. She has one way she wanted to live her life and I had another way to live mine and I was just too insecure.
"I did feel like the Phantom of the Opera hiding in the catacombs... People have actually said that I didn't deserve to be with her."
More News on Hollywood.com: