Hi Don't give up
Just wow. Your name says it all. I can only imagine the strength you have to get out of bed every day; having said that, I can absolutely see that you would have to be nearly at the bottom of your mental, emotional and physical strength.
A support network to get through all of this would be absolutely essential. Living in a rural community myself, I realise the wider community is there for each other in times of bushfire and drought, but I hope that in addition to this you also have close friends who are stepping up as much as they can to try and be there for you.
All I can really say is that your words and emotions are completely valid and it is absolutely ok to feel like this; you've soldiered on for so long, it is ok to be exhausted, drained and just done. It's not fair, you're absolutely right. And it hurts so much, because we're conditioned to believe that if we work hard and do everything 'right' then we'll have a great life, and be rewarded. Which is true for some, and not true for others. And I think it's really important to acknowledge life is incredibly hard for you and your family right now, and you're still managing to put one foot in front of the other and getting through another day. And that alone makes you tough, but it's ok to acknowledge how much you're hurting too.
I hope that life does give you some good moments from time to time - laughing with a friend, or a cuddle with your husband, or watching your child do something amazing. And I hope those moments of light will carry you through the darkness of this time in your life, until eventually the dawn arrives and your life starts to become better again, whenever that may be. It will rain again, your mum may improve, your mental health recovery will start.
Best wishes to you and your family; you have to put your head down and plod through the darkness and the cold now, but the dawn will come.