Doctors discovered last year that the 88-year-old had two aneurysms, after tests were carried out following a fall at his Surrey home.
Lady Wilnelia, 59, said the operation had sapped the energy of the former Generation Game and Strictly Come Dancing host but that he is in “incredible shape mentally”.
She told the Mail on Sunday’s You magazine: “The operation took his energy because of his age, there’s no question about it.
“Some days are better than others. On the not-so-good days, he tries to rest.”
She said she found it difficult to think about a future without her beloved husband of 36 years.
“I don’t think about it too much. I hope I’ll be prepared somehow, but it doesn’t feel real. He’s the man I fell in love with because his brain is there.
“He has a bit of a problem moving, but we still laugh and talk. I pray, I believe. The main thing is that he’s doing well. The pain is more emotional; sometimes we cry, but mostly we laugh.”
The Puerto Rican 1975 Miss World winner said her husband enjoys spending time with his grandchildren and still has a keen interest in TV, watching the Olympics, The Apprentice, and Question Time.
She said he also loves puzzles and the internet.
Lady Wilnelia said she hoped he would be able to perform again, but added: “He doesn’t want to do anything publicly until he’s 100% well. I respect that.”
Sir Bruce has been out of the limelight recently, having been too frail to attend the funeral of close friends Ronnie Corbett or Sir Terry Wogan.
He announced that he was leaving Strictly Come Dancing in April 2014, after nearly 10 years as the presenter of the show.
But over the years he had showed no signs of slowing down and in 2013 stepped out on to the stage at Glastonbury to a standing ovation, where he performed a host of classic songs and teased Rolling Stones frontman Sir Mick Jagger