Generally, we're all doing the best we can.
When someone speaks to you curtly, disregards what you say, performs what seems to be a thoughtless gesture or even an outright evil act, think to yourself, "If I were that person and had endured the same trials, borne the same heartbreaks, had the same parents, and so on, I probably would have done or said the same thing."
This does not mean we condone evil deeds or endorse the idea that different actions carry the same moral weight.
Try, also, to be as kind to yourself as possible. Do not measure yourself against others or even against your ideal self. Human betterment is a gradual, two-steps-forward, one-step-back effort.
Forgive others for their misdeeds over and over again. This gesture fosters inner ease. Forgive yourself over and over again. Then try to do better next time.