It is sometimes hard to forget the events that left unmitigated effects in your brain. Your brain is a very effective organ; it retains memories in your mind. The life we are living, The friends we meet and the people who come in and out of our lives leave some memories, and those memories have effects that depend upon the effectiveness of the thoughts. Most of the time we forget the things, messages, memories that have negligible effects on our lives, however, we retain those bullying, harassment, scolding, and bad memories, and it is scientifically proven our brain retains those things which we continuously think about.
So, If you want to live a happy life, try to forgive everyone because forgiveness is the key element to easing yourself and forgetting your past; realize that it has happened to me from now I have to be cunning before speak, acting and utter anything.