The only direction that change can be enacted on is the future.
Recognizing and accepting this truth can serve as a kind of liberation, permitting you to relinquish persistent thoughts about past events, things you could have said differently, or done differently.
In gently letting go of these thoughts, you open up additional space in your mind that you can grant to other things: thoughts of gratitude, thoughts about a project you care about, or perhaps thoughts about what action you want to take to inform your future.
There are no do-overs, just forward motion — a perpetual state of possibility wherein you can do something in this moment that has the potential to alter what is possible in the next.
Never mind the past. Instead, ask yourself what will matter most going forward? What decisions and actions can you make right now in light of this?