Give the memory of that person the chance to help you by insisting on remembering the beautiful experiences that united you. The painful ones which separated you will need no coaxing from the memory. Turn your anger into love. Take the qualities you found in the other person and develop them in yourself, use them as a way of better experiencing your love for all the others who are important in your life. After all, those were qualities which brought you into love and they are no less worthy today.
Love has no guilt and no boundaries.
In fact, it has no definition. Yes, it is the force which takes us out of ourselves so that we may share ourselves with others. Yet it is also the force that leads us into ourselves, so that we may understand and prepare ourselves for the act of giving. You cannot resolve the bitterness and pain of the separation you are experiencing by continuing to dwell on these feelings. Come alive with the force which is the essence of life itself.