My sister died yesterday, but the weeks preceding her death were filled with some horrific incidents involving choices her husband made (refusing her pain meds, chastising her for not trying hard enough, not letting anyone help her, keeping family members out). Needless to say the entire thing was way more painful for everyone than it could have been. We do feel that now that we know who is really is, it's hard to have him in our lives. It's hard to see him and not be reminded of all the things he did. Are we missing something?
Sometimes we see the truth of things, but our mind (chock-full of false morality) says, "Don't judge so harshly." Of course, we must watch for any self-creating self-righteousness towards others, but knowing the nature of something, of anyone... is the seed of our actions toward the same.
One's nature is invisible, but one's actions are its body (of evidence). You have seen what you've seen. Do not hate, as best possible; but neither should you allow parts of yourself that want to be seen as a "compassionate" person convince you to act against what love has shown you is real and true... about others (or yourself).