Someone has rightly said that your overall attitude and character can be judged to some extent by the way you treat not those who love you, but those who can do no good to you. These words are sufficient enough to answer this question. A hidden message in this can be understood in this way. What is the big deal if you love someone who loves you? Someone loves you and you love him back is quite natural. But the real test comes up when you have to love someone who doesn’t like you.
Giving love in exchange of hatred is not easy. It requires courage and endurance to live up to such a feeling; a feeling to wish the best to those who have developed lesser or greater amount of hatred for us. It requires the power to forgive such a person and wish him the best for his life. It requires the will to stay indifferent to the thoughts which can only develop negativity and aversion. It requires a will to work on the development of high morals and qualities within own self. Once you understand this and accept this part of human nature and develop a will to become such a person, only then you will be able to let go of someone who has mostly hurt you.
The point is straight forward. It is about what you give importance to that will be your destiny. If you give importance to such petty issues and a negative mindset, then it will not be easy for you to let go of such issues. If you give importance to your self-development, then your mind will focus more upon that and let go of such issues and conflicts in life.
What is exactly needed is the right thinking and once you develop that, you yourself will witness the change in you. In the initial stages, it will not be that easy to develop such an attitude. It can be done with constant practice and in a step-by-step way. Initially what you can do is learn to be a witness to activities going around.
For example, imagine you are watching a movie. All the drama and action is going on in the movie and those are not your feelings. So becoming a witness means, just to have the knowledge of what is going on and not becoming “one” with those activities. So suppose you face a person who has mostly hurt you. In such a situation, think about all those actions of that person as his own and not yours. Prevent yourself from getting one with his actions. Prevent yourself from getting influenced by his actions. Perceive yourself as physically and mentally separate from him. You will realize that it becomes really easy to let go of the issues like that.
Also, along with this practice, contemplate about the positive emotions like love and forgiveness. Developing these emotions overnight is not easy and hence with the above mentioned practice, contemplating about such emotions and slowly putting them into action will make you immune to the feelings of hatred and anger. You will not only develop these qualities specifically to deal with this case, but your overall character and personality will take that shape which will truly be a surprise for you or anyone else.
So at the end, it’s all in your mind. It’s about the way you perceive situations and give them importance. It’s about your preferences in life. It’s about your outlook towards life. This attitude of yours will not only help you but will also be an inspiration for others.
Hope this answer helps!