I am so sorry to hear about your friend's diagnosis. But, as you have said, she has given up and doesn't have the will to live. She is lucky to have you there for her. She will need someone during these next few months. The one thing that I want you to realize is that SHE has made her decision. You did EVERYTHING that humanly possible that you could do. It is not easy to sit by and believe that the choice that someone has made is the wrong one. Especially when you care for that person. Just be there for her. Let her know that someone cares for her. As you said, she wants to be w/ her husband and it sounds as though she will be soon.
I hope that she has gotten the help that she needs from DFS. She will need the medical coverage for meds, even if she has chosen not to have chemo. Sometimes radiation will help w/ the pain. It might be something that you can check out and discuss w/ her.
Please continue to come here and post and let us give you the support that you will need.
Again, she is lucky to have you for a friend.