Hi @Salpac
Being run off your feet without any appreciation is so exhausting!
Are there any community services you can engage with to help? Here is some information on what the Government offers in terms of assistance for the elderly and their carer. Often there is also local organisations that can help out too.
ARAFMI, Carers Australia and Mind are some orgs that jump to mind who could point you in the right direction based on your location.
Also, could you make life a bit easier for you by ordering your groceries online? Both Coles and Woolies offer this. I use this and it is SUCH a weight off. Funnily enough I also save money because I only buy what I need!
I also can't recommend enough seeing someone. Your GP, a counsellor and/or psychologist. You go above and beyond for your father, it's now time to go above and beyond for yourself.
Take care