The Voice coach says he should have forced her to seek treatment much earlier.
Melinda, his wife of nearly 60 years, died of lung cancer aged 75, and asked if he blamed himself, Sir Tom said: “Yes.”
In an emotional interview, he told the Daily Star Sunday: “You do start to think, ‘What if I had forced her to go to the doctors?’
“Because she didn’t go. You think, ‘S***, maybe I should have said she had to’.”
Tom’s world fell apart when Melinda lost her cancer battle in April, 2016.
At his lowest point he convinced himself he could have done something to save her.
“You do start to think, ‘What if I had forced her to go to the doctors?’ ”
Tom, 78, said: “After I lost my wife, lyrics to a Bob Dylan song reminded me of her. It’s called What Good Am I?
“I was reading into the lyrics thinking , ‘Jesus Christ …was I partly to blame? Should I have woken up before?’
“By the time we found out about her cancer it was too late. I thought, ‘What could I have done?’. It started to mean more. So that song is very touching.”
Tom and Melinda were childhood sweethearts, and wed when they were both just 16.
He said of her death: “When something like that happens, it’s so devastating you don’t know how to deal with everything. It was something I’d never dealt with before.
“I’m human. We’re all human beings first and foremost.
“When you lose someone that you love it can kick you in the…if you really love somebody and they go, that’s hard.
“But you’ve got to try or you’ll crumble completely and other people will suffer. You’ve got to think about your family as well.”
Tom has continued to perform as well as being a coach on The Voice, which returned to screens for a new series last night.
One of his biggest hurdles was singing What Good Am I? again, because it brought back memories of Melinda.
He said: “When she passed away it was such a blow. I didn’t know whether I’d be able to do that song again.
“It was the one song I was scared of because she loved it.
“I had therapy in LA. The therapist said, ‘Don’t make any drastic moves right now, give it a little time’. I told her about the song and she said, ‘That’s the first one you should try. Get the one you’re scared of over with’.
“I thought as long as I could channel it with balance then I could return to music. I tried it. I got some of my musicians together and that was the first step. And doing that really helped.”
He said: “Time is a healer. Things sink in and you realise, ‘this is it, this is the way it’s going to be’.
“So you look at it more realistically as time goes on.”