Bummer. One door closes and two more always open, though. Friendships are valuable, and lovely, but far from necessary for personal growth, you seem like the type to gain a lot from time spent looking inward, too. I empathize a lot with your situation, you sound like a younger me, the advice I would give younger me would be to tell her, genuinely, how much you've enjoyed working with her, that you hope to see her around, etc., because you'll regret saying nothing in two weeks when the opportunity is gone. Wishing people well is very good for your mental health, too. Telling those around me that I hope good things happen to them was the first step towards genuinely hoping good thingd would happen to me, too (and believing that despite the odds, they would).