As much as your heart is breaking right now (and believe me, I know how it feels!) I think the best thing to do is move on. For now. If it's meant to be (geez I hate that phrase) then I'm sure the two of you will catch up later when she's at a station in her life where she can decide for herself what she wants without outside input.
Sometimes people come into your life for a reason. Maybe your relationship has run it's course, served it's purpose, or maybe it's just beginning and this is a mere plotpoint. Don't get your mental knickers in a twist about it though.
Here's to silent heartbreak hey? :straight: