At least the thought in advance, of wanting to do wrong, should already be a shame for the one who professes evil feelings. If someone betrays you, it is he who should feel bad. No, you who gave the best of yourself. Do good and it doesn't matter what others do. Their decisions will be their own burden. Their mistakes are not your mistakes. So the improper and absurd nature that human beings show. It is always a choice.
You are right.
We should not allow the wrong of others affect us in any way.