All I can say is it will take a long time unless you get closure (which is unlikely).
I had a situation like this that happened over a decade ago and it still comes to mind. I even had a few outings and run ins with her afterward (a few yrs later after complete silence), but those wounds cut deep and they still sting a little if I really think about it.
Eventually it will be a distant memory, but for now, just look at whatever is positive in your life. I wouldn't count on getting closure, so just have your mindset accordingly. If you happen to run into her, chalk it up to a happy coincidence...your heart will probably pound out of your chest. You'll still likely have dreams for years to come.
Once you find the right woman for you, you'll wonder why you ever dwelled on it...at least that is what happened for me.