Wow OP 😱 he really doesn't GAF about you or the DC does he 😢.
Nothing excuses this behaviour. Nothing at all. It's not acceptable to behave abusively just because he's scared. Be aware he's projecting a lot. Things he's done he's accused you of doing. Don't start believing you need to make it up to him. You've done nothing wrong.
In the other hand he has:
Tried to steal your appointment,
Got angry at you when the doctors wouldn't allow it,
Told you he hoped you had cancer FFS,
Blamed you for everything that may or may not happen to him,
Ignored your feelings as if you don't exist other than to serve him,
Refused to take you to your appointment as punishment for not doing what he wanted you to do.
He's utterly appalling. Truly.
I suggest you focus on DC exams and soothing your own hurt in private. Lean on your friends, don't hide the way he's treating you because you're afraid they'll judge him for it. He deserves to be judged for it! And you deserve some sympathy and support. Don't deny yourself that just to protect his public image.
Leave him to stew. His preparation is his business, let him find a friend to take him to his appointment like you had to, I'm sure you need some space away from him to relax and recharge, living with such an awful husband.
You don't owe him jack-shit now, not after the way he's treated you. I wouldn't be "all in" for him if he has cancer either. I honestly couldn't come back from this. He has behaved appallingly. I'd be separating as soon as the exams were over and telling DC exactly why.
At the end of the day if you let this behaviour go, you're giving him a green light to do it again. Abusive behaviour tends to get worse over time, each time being worse than the last. After all, by their reasoning, you put up with the last time so it must be ok. Boundaries get pushed more and more and before you know it your in the shit and can't imagine leaving.
It's already started. I can tell because in response to wanting to have your appointment, you said ok and tried to swap it. You didn't stop to think that you need this appointment. The doctors put you on the two week pathway, it's not for him or you to decide that isn't necessary. Tells me you're already used to cowtowing to him and his whims without questioning the reasonableness or otherwise of the demands. Get out while you still can, before you feel too old and beaten down you can't face it.