End of life without drugs: Is it really the best option?

My aunt, who is 97, has chosen to die at home, without any drugs. I'm her sole caregiver. She has Stage 4 heart failure, scoliosis, glaucoma with blindness, and bouts of recurring and painful shingles. She is also bedbound. She has three Advanced Directives signed - a Living Will, a MOLST form, and a DNR, all stating that she is not to be given artificial nutrition/hydration or intubation and has adamantly stated multiple times, on video, that she does not want to go to the hospital, engage with Hospice, or be given morphine at the end; she wants to "tough it out" - her words - and die a "natural" death.
Over the last month or so, she's slowly lost her appetite and eventually was only able to drink small amounts of Ensure and water. She began to show signs of dehydration. I called her doctor, and he reassured me that it was normal and natural and suggested we call Hospice. I asked her if she would mind if Hospice came in and she said she would prefer they didn't - probably based on our bad Hospice experience four years ago. Hospice service in our area is not good and at that time had actually made things worse for her.

About ten days ago, after a course of Valocyclivr prescribed by her doctor to combat what we thought was a dangerously spreading case of shingles, she appeared to have a mini stroke. Because of her directives, and because our hospital does nothing for minis but send you home with aspirin therapy, I didn't transport her. After about 24 hours she was able to speak, drink, laugh and consent so I told her what had happened and asked if she wanted to be hospitalized. She refused "no matter what happens."

Over the last three days, her condition has degraded. She's unable to swallow. She has bouts of erratic breathing. She can't speak. She is asleep most of the time, but wakes up once in awhile and makes a small groan/grunt at which point I give her licks from a water pop until she pushes it out of her mouth and goes back to sleep. She has told me she feels no pain. The last time I asked her if she wanted morphine, about two days ago, she angrily said "No, no, no, NO! I SAID NO." So I guess that's a no. Because we knew she was dehydrating, I asked her if she wanted to be put on IVs. Again she refused.

The night before last, she managed to speak long enough to lash out at me and tell me she felt "like a fool" and she guessed I was going to throw her "one long pity party right up to the end." I guess because I was trying to comfort her. We've had a pretty good relationship over the last five years of caregiving. Although she could be emotionally abusive and throw unwarranted guilt in our younger years, we had grown close through this and I didn't expect her to "turn" on me although I know that can happen at the end. I'm not so much concerned about that as I am about the fact that I feel neglectful, guilty, scared, and confused by the results of her adamant insistence on dying naturally - as if I'm causing her death, as crazy as that sounds. I cry a lot privately. I do have siblings for emotional support who trust my judgement. I'm not pretending to believe I'm the perfect caregiver, I give myself about a B+ through the whole thing. But her doctors, lawyer, relatives, and my friends have all said I've done my job and well.

So my question is: Why, in spite of all of her wishes, do I still feel responsible for this outcome? I don't have a problem letting her go; we've said all that needs to be said and love each other very much. But how is this "natural death" superior to being drugged out of your gourd in the hospital? And I'm not being flippant here at all. I really wonder if this is better, and am I doing the right thing? If she is really really struggling at the end, should I give her morphine in spite of her wishes? Thank you for any insight you can give.