How do you know when they’re at the end?

My mum was diagnosed with cervical cancer 7 years ago and after surgery and radiotherapy went into remission. Last may she was diagnosed with a sarcoma carcinoma which had spread to her liver, lungs, peritoneum and bowel. After intensive chemotherapy during lockdown she has had to stop all treatment as she became too unwell. 

I feel like the doctors have just given up on her and are just leaving her to deteriorate. She has no quality of life and spends every day suffering. She can barely walk now from the side effects of the steroids and can only manage a small mouthful of food a day without being sick. It feels like she got very sick very quickly but is now just like this. 

I don’t understand what happens next. Is it obvious when someone is going to pass away? Or will I just receive a phone call one day from my dad saying she’s passed? How can someone continue to live with such a poor quality of life but not get any better or worse. 

I am a veterinary surgeon and spend every day surrounded by death and cancer. I’m struggling to hold it together breaking a diagnosis to clients or listening to my colleagues talking so casually about cancer. I’m trying to stay strong for my family but every time I visit I feel myself sinking further and further in to a black hole. 

I just don’t know where it goes from here or if we as a family have to spend years watching my mum suffer. 

Any advice or preparation would be appreciated x