Well, from what I know of Deathnote, both main characters have already made the decision to follow their definition of what is "right" and see it to its end. Fate, however, reflects much of the OP in that one's own morals are brought into question. My post itself is largely based on Fate. Given the nature of the situation, no matter what you do, you will always be accused of having done the "wrong" thing by someone. You just have to recognise that you've tried your best to uphold your morals, realise that not everyone will agree with your morals and move on.