Trying to except there isnt much time left

My name is vera,. In 09 my mom was diagnosed with stage 4 breast cancer. The surgery consisted of removal of the rt breast and 20 out of 22 nodes removed. After countless changing of treatments my mother now age 77 is in the last stages of her illness. Treatment has stopped cause it just isnt working. Trying to keep it all in when i take her to see the dr is a difficult task at best. I have friends that are supportive of me., but for some reason im afraid to let go and have a good cry. Just seeing my mom struggle to be independant to the point ywhere she cant stand anymore than a half a minute. Not once does she complain. She just keeps at it and say " I can do" even though it takes every ounce of energy. She now is talking to people that arent there and is aware of this. My mom still has all her marbles. Im just wondering if anyones parent,friend, had experienced the same thing with talking with people.that arent there. Does this mean her time is near.y She often talks of my grandmother and sister that she misses them more often now the ever before and they have been past for many years.