1) You're not alone!
2) Things will eventually got a LOT better, and when they do, you'll find that you are a better teacher because of your efforts during this crazy time.
3) Kids need band, and they need you.
4) Find another band director or colleague to share your experiences with, and perhaps get ideas from.
5) I know you must work long hours...but try to find some time to totally get away from it. (I know...easier said than done, but crucial!)
6) Be upbeat with the kids, but also be frank and sincere. They are frustrated, too.
7) Exercise. Walk the dog.
8) Watch less news on TV.
9} Keep working on that positive outlook, and if you are so inclined, seek spiritual strength.
All the best to you as you work through this!