The British actress, 45, passed away after suffering a traumatic brain injury in a skiing accident in Canada and Neeson admits there are times even now, as the fifth anniversary of her death approaches, that he cannot believe she is gone.
In a candid interview with CNN newsman Anderson Cooper, which will air in the U.S. on Sunday (23Feb14), he says, "(It) was never real. It still kind of isn't...
"There's periods now in our New York residence when I hear the door opening, especially the first couple of years... Any time I hear that door opening, I still think I'm going to hear her."
The Taken star claims the grief of losing his wife of 15 years has never gone away: "It hits you. It's like a wave. You just get this profound feeling of instability. The earth isn't stable anymore and then it passes and it becomes more infrequent, but I still get it sometimes."
Neeson also recalls the moment he first laid eyes on Richardson after the accident, as she lay lifeless in a Canadian hospital, and reveals the couple had previously made a pact with one another to "pull the plug" if either of them had been left in a vegetative state - so he knew exactly what he had to do.
He says, "When I saw her and saw all these tubes and stuff, that was my immediate thought: 'Ok, these tubes have to go. She's gone...'
"I just told her I loved her, said, 'Sweetie, you're not coming back from this. You banged your head. I don't know if you can hear me, but this is what's gone down. We're bringing you back to New York, all your family and friends will come.' That was more or less it."
Three of Richardson's organs were donated to help others following her death and Neeson is proud there was some good that came out of his loss, "It's terrific. And I think she would be very thrilled and pleased by that, too, actually."