I'm so sorry. What a coward! Did she get to be the expert she is in one week of *watching*? Why didn't she throw you to the wolves, so to speak, like on Wednesday afternoon and evaluate how you work under pressure? And be there to guide you for those last two days?
Hang in - breathe deep. It's happened to me so badly that I haven't worked in two years! At a *real* job! Long story!
I learned the hardest way possible to not trust a boss with any medical history that pertains to anxiety, depression, or personal changes. List meds, but offer no details.
And remember - what goes around, comes around. Be the bigger person, kill her with kindness, and when finally you are where you should have been to begin with but didn't realize, she'll have burned all her bridges. Or moved back to the one she came out of to begin with