"I haven't gotten past the place where I'm [not] putting a pillow where she was and covering it up," Chapman told Entertainment Tonight's Kevin Frazier.
He said that he cannot get a solid night's sleep, because he was so used to checking on Beth during the night while she was battling cancer.
"I wake up to always touch her, especially when she was sick I'd have to wake up a few times when she stopped breathing. I couldn't hear it no more," he said.
After her death, Dog said he can't muster up an appetite. "I can't eat. Two bites, I'm full. I got to force feed myself like I force fed her," he told Frazier.
During the interview, Dog sat next to a box containing Beth's ashes. He revealed that she wanted some of her remains scattered, but also wanted some left on the mantle above the family fireplace.
Beth's funeral service in Colorado will be broadcast Saturday from the Christian Heritage Center in Aurora.
During the memorial, Dog is expected to play a montage of fan tributes and messages.