Your quote: My exH is constantly saying "I can't undo what's been done".
When I hear this I want to scream. Yes if you were a computer, you can't undo.
But the key word here is 'can't'. I can't turn the clock back. I can't help falling in love. I can't help myself. People say it all the time without thinking about the meaning.
Can't means 'able to'. What the person means is 'won't'. I will not undo...I will not turn the clock back. I won't help myself. I don't want to.
I won't even go into what I think of these analogies--we are humans with minds and choices, not clocks, not computers, not kettles boiling...when you talk of paths or forks in the road, that's different because it does picture a thinking human being deciding what to do.
Just my rant. If I could find the MLC script, I would have such a good time editing it!