What if a narcissistic mother needs more time then you can give?

I feel stupid asking this question because there really isn't any solution to my problems that I know of. I guess I'm hoping against hope that there is something I'm missing, but I feel I'm only blowing off steam.

I really am at the point of wanting to just pack up and disappear for a few months just to find some breathing space, but I'm too responsible to consider that. I have so much on my plate at present that I feel as though I'm juggling time-balls and going with the one that falls in each moment.

I work full time 4 days a week and the 5th day is spent book-keeping for our business. I have a narsisstic mother who broke her humerus 2wks ago and has just today been released from hospital. She lives independantly but relies on me to caregive where I can with shopping, bill-paying, meals and extras like emotional support that I feel I don't have within me at present. I also have a sister 17yrs younger then myself, who has no driving license, works full time, a single parent and is unable to contribute to our mother's care in any way that is helpful to me. I have one brother left living who is simply incapable of assisting due to mental/psychological problems supposedly brought on by my mother in his early life.

I also have an aged unwell father of 85yrs (not attached to my mother), who raised us, whom I would love to have the time to spend with.... knowing it's impossible to do so.

I am also dealing with a son/mother rift of 5mths along, that is growing bigger by the day. because my time and presence of mind leaves me incapable of dealing with sorting out our issues. My mother & life responsibilites swallows up all my time.

My older brother passed away in March and I've also had the stress of being dumped with sorting out his estate which I had to finally relinquish due to my mother going back into hospital again after being there in March while my dying brother was in hospital.

My partner is struggling with health issues that have stopped him from working at age 57yrs and I find myself having to carry finances on top of everything else.
I'm really at my witts end and find it hard to breathe at times. I don't know where to turn or how to find time to even clean my house. My solace lately is this computer and a drink at hand which is not a good thing!

My mother has been afforded Transitional Care for a number of weeks to help her in her home. Things like showering, cleaning, etc, but it doesn't cover those areas that require my involvement. She is so immature and I find myself having to play the role of mother to a child instead of receiving the motherly support I would love to know.

Any suggestions anyone? I'd appreciate productive solutions. I also live in Australia which makes a difference to medical/home assistance to many here. Thank you ahead of time.