Sheena
I can understand why you're feeling the way you are - good grief, if any of us had been treated the way you were I think we would probably feel the same way too.
I find it difficult to understand why the principal felt the need to react so strongly. Is she just a mean spirited person? She really doesn't need to be in the position she is in if she is. For all she knew you could have been having a stroke - did she offer to call paramedics or your doctor? Sounds to me like some sensitivity training is in order for this person.
I've been reluctant to leave the house when I'm in the midst of a flare up - just because I know what to expect now and know my limitations. If it's not absolutely necessary I just don't go or I wait for my son to get home.
Have you looked into home delivery for groceries/necessities. I know of several stores here in the state I live in that offer this. Or call your NMSS office and ask them if they know of any services that might help you.
You will eventually have to leave the house - if I were you I would discuss this incident with my Neurologist and see if he might be able to prescribe something that can help you over this hurdle.