We are ordinary human beings and so our actions at times are not necessarily perfect in one way or another, so we do make a lot of mistakes.
If we truly understand those individuals who make others unhappy or angry, it is not because they really want to, but obviously is due to their emotions which make them vulnerable to it and its ill effects. Moreover, sometimes even we may be affected by such poisons. As a person, the best option that we have in front of us is to learn to forgive and forget for those who are totally infected by anger, confusion and jealousy. I personally feel that it is for our own interest. When someone comes and says I am sorry for my mistakes then we should simply say ok I accept your apology because at least we are doing something morally right. Have a wonderful day.