I'm very sorry you have lost your dear dog, your best friend & companion. I'd've done anything too, if I could have, to save my own cat. Today, I still find it hard to fathom just how much I loved her, just that I did, & still do. It's hard for many people, to understand how deeply some people care for their furry friends, & even I don't really, & I've done it.
I don't know where you live, but I am sure there are organisations who can help you when you can't afford groceries. I'm thinking of The Salvation Army (Salvos) or Anglicare, & I'm sure there are more.
A quick google of something like:
Can't afford groceries, who to call Australia
which is what I wrote in the search box, can help you find help.
It won't be easy, I'm sure, asking for such help. I wish you the best.
I'd love to hear stories about your dog. There is a thread, Pets gotta love them. (that's not quite precisely how the title is, but if you would like to honour your dog there, as I have posted about my cat, I would love to read post/s from you.
If anyone reading here can help with a direct link, that would be great.