What worked for me/us was to let it lie for a while and demonstrate that nothing has really changed. Mine has said that regardless of how i feel now, she is unsure about our future together. her vision of what that looked liked has changed. My reply to her is I'm willing to compromise to an extent, as losing her would make my life suboptimal.
Both of you are likely going to have to live with a small amount of doubt in her mind as to your possible end state. My feedback to my wife is no one is guaranteed tomorrow, and a multitude of horrible unforeseen stuff could happen, so live for today and plan for a tomorrow.
