I'm sorry to hear and I wish you and your dad the best. Hope you find peace and those moments in your head prove to be a forever lasting memory of a wonderful man.

Nothing. If we were to go back in time, we'd make the same `mistakes' again as that's who we _were_ (its the cumulative development since those points in time that gave a different perspective that would make us act differently).

Most of our life is failures. Once I hit a particularly low point (and also with age), I appreciate the journey much much more as cliche as it sounds. For a different reason - with an expectation to mostly fail, we are set free to truly live.