When you have to make a decision or take a certain action, all that you can do is to do the best you know at that time, and if you do that you will have done your duty. In the light of after events it may turn out that you made a mistake, but that will not be your fault because you could not possibly do better than the best you knew at the time. The wisest man that ever lived could do no more.
For this reason, it is very foolish to repine over past mistakes which were made in good faith. Any fool can have hindsight; it is wise foresight that is difficult. Do what seems best at the time, taking all circumstances, as far as you know them, into consideration, and then have no regrets.