What was, was.
You can’t take back the past or change it. It is now part of history, and you must accept it for what it is, for better or worse.
There is no sense knocking your head against the wall, or wishing the past was different, or pretending that things went down more to your liking. What was, was.
All you can take from the past is a lesson.
A lesson of what you won’t do in the future. A lesson of what you will do differently in the future. A lesson what you won’t allow in the future.
Perhaps just a lesson that what was, was, and you can only take your past and look forward.