Confession and denial
I was wrong.
Those three little words are powerful not because they change the situation but because they change us. Saying "I was wrong" immediately stops the rationalization and the if-only-ing, allowing you to shift your focus 100% to dealing with the present reality, allowing you to start right now building a better solution.
Denial is a stubborn anchor that prevents the boat from leaving a bad harbor; you have to pull it up so that you can sail on.