My Dad struggled for the past several years with illness and dementia, but we were so lucky that he never stopped recognizing us. His personality and appreciation for life stayed with him till then end. Our love goes with him.
I am so sorry for your loss. May you find comfort through the loving and happy memories of your dear loved one. May you also look to our loving Heavenly Father, the God of all comfort, to provide what you need at this very sad time. He promises us that there will be a resurrection of our loved ones that we have lost in death, and they will have the opportunity to live forever in perfect health in Paradise right here on earth. (John 5:28,29, Psalms 37:10,11). May all of God's promises give you a measure of comfort, peace, hope and strength. I have personally found very comforting thoughts on jw.org.