I answered your other post. My grandmother died due to drinking, it was her liver mostly, but her other organs where weakened. She was only 58. We did everything they told us to do and in the end her heart gave out because it was so weak. For me I would have to tell you that this is a personal matter. I'm not a nurse or have any medical background.
We recently went through something similar with my aunt who was 51 but she had in place a living will so we followed her wishes. I am so sorry. I just want you to know that once her CO2 level got to a certain point she never really came back. We knew that she didn't want life support. That would have been the only option when the smaller breathing treatments failed, but I think you are at that point already. I know I wasn't much help, but I wanted you to feel someone was here for you this morning... praying and trying to listen...
With you in spirit...