Looking for advice

Hello. This might be a long post so sorry in advance. I also hope I dont come across selfish in this post for i have been feeling that way lately.

My mum was diagnosed with stage 4 cancer in January this year. Pre-diagnosis, she was extremely strong and was the centre of our house, who my dad, younger brother and younger sister relied on for everything. When she was diagnosed she was understandably devastated, as were we all, however, the doctors were positive about her prospects for her treatment and her ability to live with cancer. So i thought oh she will come around and take a more strong stance against this and try to fight this. Now later in the year i know now this is not the case.

It seems as if she has given up on life. She is having immunotherapy which we heard nothing but positive stories about, saying how people could still go to work and do normal things in comparison to harsher forms of treatment. But this is not the case. She obviously has side effects to the treatment and has to rest after and we are not expecting her to run the London marathon but she has just truly given up, even when no one else has. She does not leave the house except for treatment, she has missed birthday dinners etc, she does not speak to anyone about anything other than cancer, like will not ask us how our days went or if we go out she doesn’t care to ask, she always talks about death as if she is going to die right then and there, she doesn’t respond to friends or families texts to support her. However, out of them all the worst is how she treats us. She calls my brother, sister and I horrible names, she makes us feel guilty for not spending time with her enough even though we are all at school and try our best, she treats my dad horribly even though he now runs the house and cooks etc and overall she has just turned into someone who i dont even know. This impacts our mental health daily and my siblings especially feel afraid to talk to her about their days or what’s going on in their lives in fear she will call them names or talking about how she doesnt care cause she is the one who is dying. My dad is also not very well and i am afraid for his health too.

We have all tried talking to her but she says she doesnt want to talk to us and will not speak to Macmillan about her feelings or a therapist. I know talking about us sound selfish as she is the one who has cancer and we shouldn’t be complaining but i just thought she would be out of the anger and sadness stage of her journey by now but she hasn’t and now our lives are doom and gloom 24/7 as we cannot speak about our lives at all.

i really hope i dont sound awful because i love my mum and i would take her shouting at me everyday if it meant she could be here cancer free but it just feels so overwhelming and hard to deal with whilst also studying and working and whilst also trying to support my dad brother and sister . I dont know what to do because i know we all cannot live like this and i am only young and am unsure on what to do. If anyone has any advice i will try anything or if anyone has went through or is going through the same thing i would like to know because I also feel like i cannot talk to anyone of myf friends because it is too burdensome.

sorry for the long post, just hope someone can help. Thank you.