Dear @Former-Member
From the description of your friend (stoic and tending not to show her emotions openly or easily), she is quite similar to myself. Fact is, she would be going through so many emotions right now, from feeling numb to being totally overwhelmed. It's possible she is in denial about her husband's prognosis. Or she may be just trying her best to maintain her composure. To seemingly reject your support she may be protecting herself.
When my husband was in hospital in April I was initially told he would never go home, that his prognosis was grim. I was devastated, numb and went about each day in remote control mode. I was at the hospital for 12 hours every day, generally until the nursing staff turfed me out. Initially I did not tell family or friends just how bad he was. They all live a long way away and I did not want to worry them. I just kept hoping the next day things would improve.
I didn't want to believe what they were telling me. But each day the news seemingly got worse, and he had 2 episodes of near-death. I was forced to advise his immediate family members just how bad things were. Throughout the whole 4 weeks that he was in hospital I remained seemingly in control, stoic and largely emotionless. The only time that changed was if someone asked me whether I was coping. That was usually a nurse, a doctor or a social worker. Then I would instantly break down and bawl my eyes out, blubber uncontrollably and be unable to answer. So for me, to reject any prospect of support, was a self preservation thing. I didn't want support, because that would be admitting that I wasn't coping. And to accept offers of help, would have broken me emotionally. While ever I did it on my own, I stayed strong, I knew I had to.
As you are aware, hubby did come home, against all earlier expectations. They just had to find out what was causing his immediate issues. And it was after he came home and things settled back to near normality, that I suffered the most. Of course he still faces a terminal illness, which we continue to deal with daily. But the immediate thread to his life has eased.
As you are obviously a good friend, and have been for 17 years, there will come a time that she will need you. Let her come to you, follow her lead as to what she needs and when. If she gives signals that she does not wish to talk, then let it be. Sometimes it's just too hard to talk.
Probably all you can do for now is to let her know you're there for her when she needs you. I know you've already done that. But next time you are talking try to reinforce that you WANT to help her, and that you're always there for her. Ask her "What can I do to help"?
It may also benefit her to know that you too are hurting. That you consider both of them to be extended family. I know its not about you right now, but it may help her to realise that she isn't alone in her grief and pain.
When she does need to talk and unload to you (I'm sure the time will come), don't feel you have to offer answers or solutions. Sometimes there simply are none. And never underestimate the power of human touch. If both of you are comfortable with it, give her a heartfelt hug or place a gentle comforting hand on her shoulder. No words are necessary, just a caring gesture of support.
She told you that there is nothing anyone can do. Well, she's right, there really isn't. But try not to let her apparent coldness deter you. People in the situation of having a partner facing a terminal diagnosis go through stages which includes anger, fear, disbelief, denial and helplessness. It's likely she's in the helpless stage, given that it appears that all hope for recovery is now lost. Thus her comment "there's nothing anyone can do".
Each of those feelings or stages, are very difficult. But due to the type of person she is (stoic and reluctant to show her emotions) she would likely be having great difficulty in confiding with anyone or in revealing her feelings of fear, vulnerability or anger. And yet, that is what she really will need to do.
I know you are hurting badly right now, feeling as though you've been rejected. But I very much doubt that's the case. Don't give up yet on her or in the investment you've put into whats obviously been a lovely 17 year friendship. Good friends are hard to find, and worth persevering with to maintain.
I don't know if any of this is helpful to you? I hope it is. Though, I'm sorry my first attempted reply was lost, as it was so much better than this one. Sadly, yes it was. 
Sending you love and a caring hug.
Sherry 
