I'm sorry to hear this avenger. spend as much time with him as possible. do any little thing that he wishes to help him feel comfortable. try and bite your lip
and take a deep breath to relax yourself if you are starting to find it frustrating. what he is going through its much worse than what you are going through.
I used to do all these little things for my wife and she appreciated it so much. I said to her that she need not say thankyou as it was a pleasure. she said, all these little things that I found insignificant gave her great relief as she was unable to do them herself anymore
you will have less regrets afterwards.
after this experience caring for my wife, I changed quite a fair bit. instead of thinking about me first, I now think more about others and not to be so complacent about loved ones including friends. i.e. that they will not always be there.
I have a lot of photos of my wife but one thing I have little of is recordings of her voice. and I do miss hearing her voice especially getting me when say I have come back from an overseas trip