[ElaineM]

I don't have any rock solid advice, but let me throw a few things into the ring for you to think about.
You have a difficult decision to make. Can your employer give you a less physically demanding job or shorter hours at least temporarily?
Do you feel comfortable talking to your principal about this? Every boss is different. Can you talk to human resources about this without creating issues? I used to work at a school as a teacher and my mom was a school secretary, so I kind of understand your situation a little.
Your 14 year old seems like a pretty bright kid. Would your 14 old be able to apply for scholarships and/or a good financial aid package? Maybe it is time to check with your 14 year old's school to see what might be available a few years from now.
Is your husband healthy enough to work a couple more years part time? Would you be able to get a part time job in a less stressful job when you are able to go back to work?
All the best to you whatever you decide. The main thing is to take good care of yourself, so you can recover enough to do the things you love and need to do. That is the prize. Keep your eyes on the prize.