"Feel all your feelings. Although you may need to feel angry for a while, clear all resentments from your heart as soon as possible. Say good-bye with blessings and love toward the other, thanking that person for all he or she has helped you learn. Remember that any curses you place on another will ultimately come back to harm you, too. Grieve your losses. Say your good-byes. Then let each travel down the road that he or she needs to go. Holding on won't help. Let both be free to plan their own journeys, map their own trips, and embrace and enjoy their own destinies. "-Journey to the Heart-Melody Beattie

Sometimes we have to let go whether it is a loved one or friend or job or lifestyle.  It hurts.  But let go you must.  Wanting revenge or even saying karma will get them is still holding on.  You want peace.  Forgive and move on having learned valuable lessons so you can go further on your journey.  I have had to say good-bye for many reasons.  Not easy to do.  But sometimes stumbling blocks are placed before us and we need to go over or around to get to the joy awaiting us on the other side.  Trust and move on.  Peace.