Hi Natasha and welcome to Talking Point.
Actually, I don't find your reactions extreme in the least (you may have sensed that already). You have way too much on your plate dealing with things you have to deal with that can't be put off to cope with anything else.
Guilt - it's a biggie and something we all struggle with, and it's dfiicult to deal with the guilt that comes from "Am I doing my best for the person I'm caring for?" or should that be "I must do better" . However, and this is going to sound hard, your priority is your own mental state and the care of your grandmother, and you have to harbour your resources. If that means you have to stay focused on that at the momnet, so be it.
I'll also say this though, because it's a subject that comes up time and time again on the board - don't ever say ever. Yes, you made a promise to take care of your grandmother, but there may be a time when you can no longer provided that care 24/7. If and when the time comes (and it may not) and you need to consider a care alternative, that is not breaking your promise in any real sense - you will still care, just in less hands on way.
Best wishes
Thanks Jennifer, thank you for reassuring me. I know that I won't be able to care for my nan forever, there will be a time when I need to look at alternatives, but I want to continue for as long as I can...whilst maintaining my own health and emotional well-being.