Witnessing a close person taken away by Alzheimer

The agenda of the trip I had to Québec City was a visit to one of my friend`s mother. That woman was like a mother to me. She was a very intellectual person like me. When I was in college I found a common passion with her in philosophy, especially French philosopher, Jean-Paul Sartre. Also, both of us loved visual arts, French impressionists in particular; we used to go to museums together.
She used to sew for me. She would make dresses and other garments and once we invented a new brand for her creation and we called it "Luce de Paris". We even went to make the tags with that logo!
Her and her husband introduced me to all kinds of refined French cuisine. She used to be an incredible chef. I was always flabbergasted to see all those meals she would prepare. I remember the times when my friends and I were sitting at the table and every minute with them meant a world to me. I was so grateful to her that she would share her life with me and treat me like her own daughter.
Her and her husband introduced me to another world - the world of refinement and elegance and they gave me a family I never had.
It has been 10 years I haven't seen her. I heard that she had Alzheimer and I decided to go visit her when I was in Quebec City. I was advised by my friend not to expect much, but I was shocked to see and hear what she had become due to Alzheimer.
We were in the room her, my friends and I. Every time she would ask us something and we would take turns to reply by the time second person replies she would forget what the first person said. After few minutes of being in the room I was overwhelmed with sadness and grief. I realized that my friend was gone. I kept asking her questions that would remind her of our common experiences and those "special moments" in our lives, but she could not even remember me. She really thought I was a stranger. And that hurt me so bad that I could not cope with that. At one point I started crying quietly and my friend saw me and suggested that we should go.
We walked out and I said to myself that it was the last time I will see her alive. It brought back all the dark memories of my past when my adoptive dad and mom passed away. I gave her a hug and I was really surprised that she let me hug her because to her I was just a stranger. And I finally said my last good-bye and left. Few minutes after I got in the car and fell apart.