How do I feel nostalgic and heartsick for a place I haven't left yet?

When children's voices lifted in quiet song on a windy Sunday afternoon choke tears in my throat, and swarms of dragonflies floating through branches in my orange tree leave me longing and breathless?

Mid-afternoon sun-filtered through holes in a tiled roof, in the arms of someone I'm slowly tearing myself away from yet constantly pulled toward lances through me leaving profound holes in my heart.

A pink-dressed student rushes towards me for a twirling hug shrieking "mi Callie!", her smile writes arpeggios filled with graceful treble notes.

How can I remain open to life here while braced for heartbroken goodbyes?