I think you've already had the best advice OP - take your friend's lead.
Be there for her, whether that means being a shoulder to cry on or somebody to go out & had fun with. Everybody is different, but most will have good days and extremely bad days.
I've been through it with both of my DPs - both whilst in their 60's, so relatively young to be contemplating the end of your life. DDad was mostly very positive, saying things such as "today I'm OK, and tomorrow I will be too" and "just you wait, I'll outlive you all yet"
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DMum was not, she found it incredibly hard to be positive and focused a lot (understandly) on what she would miss in the future. Seeing grandchildren (she only met 4 out of an eventual 7, and one was just a very small baby), watching them grow up, her dog who she had taken on as a rescue and was still relatively young (she needn't of worried, DB & SIL adopted him & he has lived a life of luxury ever since). The retirement she had planned (she was still an employee when she died) and so on, and so on.
There is right and wrong way for the sufferer to feel about things, and all anyone else can do is be sensitive to the way they feel and support them in whatever way helps them best.
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