“Anger (or hatred) is like swallowing poison and expecting the other person to die.” Alcoholics Anonymous
Close your eyes and imagine you could feel better about all of your bad relationships. Imagine you could stop being angry and upset and could get past whatever event or memory is preventing you from getting along with that person. The good news is you can. You choose to be angry and upset. You choose to let that past wrong interfere with your relationship. You decide that what they have done is so horrendous that you have to keep them out of your life. So make a different decision. As hard as it may seem, forgive them. Understand that whatever they did was an insult, inappropriate, and unforgiveable; but your relationship with them is more important.
Stop taking the poison and your relationships will survive and become stronger. Stop taking the poison and you will be happier.