The pain that you feel is real.
But so is the pain of the other party in the conflict.
Where you put your focus, and what pain you decide to share will be different.
But very rarely is there full transparency between parties in an interpersonal conflict. That type of reveal only occurs when trust and intimacy are high, rather than low.
Which is why, when the hurt is deep, and the pain is long lasting, the only acts that change cultures, people, and ultimately move people forward to the next step in their emotional lives, are acts of reconciliation, restoration, and forgiveness.
The kinds of acts where recrimination, holding grudges, and using information about the impact of past hurts as weapons in current battles, is not allowed.
If you enjoy the pain that you feel and you like the impact that the pain you are experiencing is making in your life, then, by all means, continue to hold a grudge, exploit the anger from that hurt, and revel in unforgiveness of the other party.
Keep this thought in mind, however: Holding a grudge against another person, about a conflict that occurred a long time ago, is similar to drinking poison yourself and hoping the other party will die.
Instead, free yourself of the pain you feel by forgiving yourself first, and then them.