@Universal it's surprising how much 'help' we don't need. I'm like an old dog when I'm sick--I just want to crawl under the bed and bite anyone who comes near me.
You've had some good advice so far. Unfortunately, there is nothing like a crisis to make folk revert to factory settings. I had to tell my mother to go home after my first diagnosis. I was OK while in was in hospital, but by the time I got home --where the really good drugs were not available---i simply couldn't stand anyone even talking to me, let alone 'helping' . She was offended, but at least she was in one piece, which she wouldn't have been if she woke me up to ask me how I was feeling more time.
Realistically, you are not going to starve and the house work can wait. You just need peace and time to adjust at your own speed. Not that we have a great deal of choice about the pace of life when we find ourselves on the BC train. But grab what you can.
Maybe try telling her you've had some advice you may need more support in a couple of months and you'd like her to come back then. Then keep putting her off until you feel strong enough to cope. MXX