You may have mistreated others or told lies in the past. You can’t do anything to reverse the event in the past, but you have two choices to move forward: to regret or to forget.
To regret is to allow those wrongdoings thoughts haunt you back from time to time, however your remorse represses you to repeat the misconduct.
To forget is to descend into repeating the same misdeed. If it never occurred to you that maltreating others is immoral, you have the proclivity to repeat it.
It is better to regret and let the agonizing remorse kills parts of your soul that serves as a reminder, than to be a recidivist who fall deeper to the dark side.