How have others dealt with a deathbed confession? When I called my dad in the nursing home yesterday, he was delirious, which I've seen before with him. But as an added twist, he added that since it's the end of the year it's time to reveal secrets and "there was another woman" in his life. Frankly I already knew....I found a letter he wrote her when I was 21 (I'm 51 now). I never confronted him or told my sibling or mother. I'm frankly po he told me yesterday and has dredged it all up again. And although I'm not fan of my mom, she goes regularly to see him and I shudder to think about him saying this to her (though I've long suspected she knows). I know confessions are normal but what a pita...and although he's in his last weeks (I think) I don't want to call or visit again ...god knows what else he'll tell me.
I think that you're making this bigger than it has to be, as you supposedly knew about the "other woman" 30 years ago and chose not to do anything about it, so choose now to just ignore what your dad says and let him die in peace with a clear conscience.
That said, I think it's okay to say to your father, "I don't want to hear secrets," and then suggest that he speak with a spiritual adviser (for example, a priest, a minister, or a rabbi).
That idea may work for you too with both of them. I hope so.
I'm sorry you've been put in this position and pray you find it easy to put it ALL out of your mind and find peace. You sure deserve it.