If you feel resentful, you are the one suffering from it not the person you resent. If you feel angry because of someone else's character defect (their impatience, intolerance, prejudice, ego imbalance, jealousy, anger, fear, etc.), then you are punishing yourself for their problem. Why punish yourself for someone else's toxicity?
Forgive the person and pray that he or she receives all of the blessings you have received (like freedom from your own character defects and love and forgiveness from others). If you can help the person heal, try. Usually, if not always, you can't do anything and your attempts will only be viewed as nagging. If the person is living or working with you and continues to foist his or her character defects on you and you feel you are being abused, consider creating a healthy boundary. A healthy boundary may come about by seeking a third party (like a marriage counselor) to help you deal with the issue. Healthy boundaries are changes you make to limit toxicity. An example of a healthy boundary is talking to a sick person only after you have eaten a meal so you are physically strong enough to not lose your serenity. Another is taking breaks at work to meditate so that you are peaceful despite an oppressive boss. Where do you need to create healthy boundaries and how can you do it? Seek guidance from educated, caring persons.