It is not uncommon for individuals who are struggling to cope with a loss to feel as the line in the song, If I Could Turn Back Time, "Over and over the helpless voice asks 'Why didn't I…?' and sobs 'If only I'd…'—but you didn't and it's too late." There are two categories where in this will develop, commission and omission. While it may not always be easy to live with regret that hindsight says we should not have done or said this or that, it is much more difficult to live with the regret of that we should have said or done. Even if this feeling is unrealistic, it remains much more painful when we feel we left undone that which we never can retrieve.
It is never easy to move forward with a traumatic loss especially when there is the overwhelming feeling of unresolved issues. It may have been words spoken in haste, angry words are lightly spoken, Bitt'rest tho'ts are rashly stirred, Brightest links of life are broken By a single angry word. When we make impulsive or poor choices for which we feel regret and remorse for the choice made and the negative consequences. We may also indirectly cause pain in others by our much-considered decision that has negative consequences for others, yet we made the very best choice we knew to make based upon the facts at the time.
We cannot change the past. What we can do is learn from our mistakes or poor choices and never repeat again. What could we have done differently? Equally important is to take ownership of our choices. Once we learn from our human error as imperfect beings, we may let go of the regret and guilt as we did all we can do to improve as individuals. No one can / should expect more.