Try,Originally Posted by green_summer
Sometimes you do things that cause you to feel regret for the rest of your life. How can I express that using an idiom?
I'm not sure about an idiom. What about?
I regret having married him. (i.e. I should never have married him)
I regret not having married him. (i.e. I should have married him)
I regret having not married him. (same as above)
All the best, :D