My heart goes out to you and your family. There are so many of us going through the same pain and frustrations with the unknown. My husband is going through so much right now, and, like your Mom, is more worried about everyone elses quality of life. I have just recently come to terms with that one. As far as time, no one does really know. We may want thier suffering to end because it hurts us so badly to see someone we love be in such a weakend state, and in pain, we cannot forget it is not about us. It is everything they have had to come to terms with. Which is far beyond any one of us who is not the one fighting and facing each day with thoughts they are hoping we never have. We can't feel guilty about it. it is not our fight. We are there to support, love, and be thier advocate when they need us. I cry with my husband when he needs to, I cry when I need to and I support anything and everything positive he needs to make it through this without feeling guilty that he has somehow taken something from our lives because he is sick. We must find our own support so they can depend us to be there when they do accept our help. They need to know we are ok. They know we are not. That's why we take the time to hold hands, and just sit for awhile and always tell them how much we love them. We show it everyday by making sure they are ok. That the doctors are caring for them to our satisfaction. Our "patients' have had so much taken away from them, we need to make sure they can hold on to what makes them the person they are, and why we love them so much. Allow them to take that with them. Thier love for you, and the cancer did not take away what matters most to them. I don't know what that is, I don;t have to. Whatever is important to them right now is priority. Don't put a time limit on a thier lives. They have fought to hard. They decide what thier quality of life is "quality" Which is time. She will let you know when she is too tired. She will not allow herself to be taken over by this. Her body has been taken, not her soul, not her heart, not her ability to love or worry about others. Let her keep whatever she feels gives her, what she believes believes makes life worth living and fighting for. If you do this, then when the time comes and she can't make that decision to keep going, you will know and will never have regrets.
This is such a personal thing for all of us. If I sounded like I was making some sort of judgement, Truly I was not. Sometimes when it is so personal, we get overwhelmed with helplessness, and look for support. Sometimes we don't even realize we were looking for it.
I apologize to you if I overstepped or just overdid it. I just know exactly what you are going through and wanted to share the same personal experience. God Bless