Spite, the desire to hurt others, indicates the absence of love and compassion. Unforgiveness leads to spite and malice — the insanity of intentionally hurting others to make yourself feel better. Malice and mercy are opposites. Mercy requires much more courage than malice.
Malice is mistaken identity, believing that evil is in the people you don’t like (or disagree with), but not in yourself. Freedom of speech guarantees the right to openly disagree with people, but we don’t have a right to verbally abuse them.
If you don’t do what you know, merely knowing it won’t do you much good. If you won’t refuse to allow thoughts that you don’t like, to remain in your mind, then they will linger and torment you.