You are an amazing human being.
Unlike you, my dad chose to display his selfishness during my mother's illness. My mother, who had vascular dementia for years, would use her walker to approach my dad in his recliner to pat his arm and tell him she loved him. He would continue his crossword or reading or whatever he was doing, ignoring her while I seethed. After she died, my dad sobbed, "I just wish I had told her more often that I loved her." I had no words for him.
You provide the model I wish to follow. Bless you, and thank you for all the knowledge you have gained from your experience and so willingly shared with the rest of us.