Metastatic breast cancer

Hey guys! My mum got recently diagnosed with stage 4 metastatic breast cancer. She firstly got diagnosed with stage 2 oestrogen positive her- breast cancer 5 years ago, now her metastasis is to her liver and triple negative. I am so lost. She is my rock and I am so consumed by the thoughts of losing her. I do believe in miracles and I hope that her body and cancer respond to treatment and prolong her life. How can I cope? How can I manage the grief that I feel while she is still here? How can I manage seeing her in such vulnerable state during her chemo? I hope she is going to be a survivor. I am so afraid that my mum won’t be here for my marriage, my milestones, my graduation, the birth of my child. I cannot picture my life without her.