O.P please write down these conversations. Even if you don’t do anything with them it might preserve your sanity if they later deny it.
If you haven’t already, get in touch with your union rep. They know this stuff inside out, it’s what you pay your subs for and in my experience they feel like they’re on your team and that’s what you really need right now.
With your diagnoses, I am sure you could get rolling sick note until May, when you hand in your notice. I know this isn’t an appealing prospect but it sounds like you are exhausted.
I am also a teacher (of 7 years) and I really value my partner’s (of 4 years) opinion on whether I should go to work, because he is a normal, non-teacher person who puts my health and wellbeing above my job (unlike me.) For example, when I was trying to leave at 6:30am for a half hour drive to work on country lanes through a foot of snow (and mounting) he rightly pointed out that that was idiotic.
Or yesterday, when I had a fever and could barely swallow (oh hello yet another throat infection) he wondered how I would speak for 6 hours, and perhaps we should go to the doctor instead. Doctor promptly signed me off for the week and gave me a gallon of penicillin.
Listen to your partner, if he says you can cope on one wage he’s a) probably right and b) worried about you. As an aside, my current job are amazing and said, we will handle it, go to sleep and stay warm.
Also while you’re off I highly recommend watching some Queer Eye. You gotta show up for yourself before you can show up for anyyyyone else.