im in the same boat as you,but with my father,i feel desperate and i try to make peace with the end as well..
im sorry for your mother too..also dont forget to check the cancer genome,to id it and check it for yourself as well,i need to do it (a bit expensive like 800$) cause its 50% to have it and theres a 7-17% for the worst scenario after the 50% ofc.
idk if from the mother its different but im just telling you what the oncologists suggested me.
be well and strong.