Natasha died in a freak skiing accident five years ago, while the couple were in Canada, leaving behind two sons, with the Taken actor.
In an emotional interview, the 61-year-old, revealed how the couple – who married in 1994 – had made a pact should one of them ever be left in a ‘vegetative state’.
He said: “She and I had made a pact, if any of us got into a vegetative state that we'd pull the plug. She was on life support [after the accident]...I went in to her and I told her I loved her.”
Speaking to CBS in an interview which is due to air on Sunday night, Liam also admitted that, even now “when I hear the door opening, especially the first couple of years... anytime I hear that door opening, I still think I'm going to hear her.”
However, the Love Actually star explained how he had found solace in her passing, revealing Natasha had donated her organs, which had been given to three people.
“She's keeping three people alive at the moment. Her heart, her kidneys and her liver. It's terrific and I think she would be very thrilled and pleased by that.”