Duane "Dog" Chapman and Beth Chapman Picture: Donn Jones/Invision/AP

Los Angeles - Beth Chapman wanted to make sure that her husband Duane 'Dog' Chapman and their family were "okay" in her final moments.

The 51-year-old reality star had been placed in a medically-induced coma last weekend after she was left struggling to breathe as a result of her battle with stage 4 lung cancer, and sadly passed away on Wednesday.

In his first interview since his wife's death, Dog called on the world to find a "cure" for the "terrible" disease.

Speaking to Hawaii News Now, Dog said: "It's terrible, the most terrible time in someone's life.

"You kind of try to remember that you're celebrating life, but right now we're mourning the death, so it's not good.

"The cancer gig, of course, we've gotta find a cure because all we have now is some get lucky, but most pass away."

On Beth's selfless final words, which she mouthed when she had moments of consciousness, he recalled: "When she had an attack I didn't know anything to do but to say 'in Jesus' name' and hold her and when I said 'in Jesus' name' she said, 'Say it again, say it more.'

"And then she told the girls and everybody, with her mouth -- she came out of it a couple times - 'I love you' and 'Are you guys all okay? Don't worry,' but she never accepted it.

"So amazing, this is totally unbelievable."

Dog also shared how his wife knew she was dying and said it was a "test of her faith".

He said: "One of the last things she said [was] 'It's a test of my faith'.

"She had faith and that was it.

"There's things you go through when you're dying, like steps like you do when you lose someone, right? "You get mad at them, and then you go through all these steps.

"Well, the last step when you're dying is to accept it. And she said to me the other day, 'Honey, that last step, I ain't taking...'

"So go Bethy."

The 66-year-old reality star joked about how Beth will probably "control" his life from heaven and admitted she was a fighter right to the end and was determined to show others how to "beat" cancer.

He said: "Beth was somewhat of a control person -- not from the grave but from heaven.

"I'm sure she's still controlling me and I've got notes in my pillowcases, on my sink, in my shaving thing. "She's still telling me what to wear.

"She did it her way.

"There's some things that they predicted that the doctors ended up saying, 'We've never, ever, seen anything like this'.

"Her way was to live. She wanted to live so bad and she fought so long, and the reason she fought, she liked life but she wanted to show people how to beat it and what to do when it got her."

Beth was survived by Dog and their children Cecily, Bonnie, Garry and Dominic Davis.