For a long time you probably rehearsed it — the moment they'd finally say it, and what you'd say back. Maybe you'd forgive them on the spot. Maybe you'd finally get to say everything you swallowed at the time.
But wounds don't wait around for apologies. They heal into whatever shape they heal into, with or without one, and sometimes by the time the apology actually arrives, it's not for you anymore — it's for them. You've already done the harder, lonelier work of getting okay without it.
That doesn't mean it wouldn't mean anything. It might still land somewhere. But it's worth asking honestly: are you still waiting for that apology because you need it, or out of habit — because you've been the person waiting for so long it became part of who you are?