to (one's) dying day
For the entirety or remainder of one's life. to my dying day, I will never forgive him for what he's done to our family. Despite all her doctors' warnings, my grandmother smoked cigarettes like a chimney to her dying day.
to your dying day
for the rest of your life. 1967 George Mackay Brown A Calendar of Love This one always was and ever will be to his dying day a garrulous long-winded old man.
till/to/until your ˌdying ˈday
for as long as you live: I swear I won’t forgive her to my dying day!