The legendary entertainer died in hospital at the age of 88 in November, a week after suffering a fall at his home - despite appearing to be on the mend.
Now Wilson, who was O'Connor's fourth wife, has opened up on his battle with Parkinson's in the final few years of his life.
"Des dealt with it very privately," she told the Daily Mail. "He didn't want people to feel sorry for him and for it to be what they first thought about when they saw him.
"He was diagnosed in 2017 but he thinks he had had it for a while."
She added: "Des wanted people to be uplifted chatting to him, rather than thinking about his illness. It was a very gradual thing.
"When he was told, he was very upbeat about it. He dealt with it, saying, 'Yes I've got it, but I'll keep taking the tablets and keep smiling.'
"That's what he did: took the tablets and kept smiling."
O'Connor is survived by Wilson, four daughters and a son.