Tragic news :(

Kinda sad this morning because my brand new Ginny galaxy I just got 20 days ago (and spent $50 on) developed powdery mildew. I realized about 4 days ago and doused it in copper fungicide, which fried most of the remaining leaves 🙃 I have faith she will bounce back, but man is it disappointing. Luckily, it was quarantine so my other plants are fine. Any other advice would be appreciated.