I'm so sorry this is happening to you,no wonder you need to vent and cry.
But loss of speech or loss of life?
I can tell you I worked for many years with children and young adults with no speech or limited speech for a wide variety of reasons--it was just amazing how they coped, even the ones who had been used to a life WITH speech. Modern technology, gestures and signing, good old pencil and paper can overcome a lot of the practical problems.
But--that doesn't alter the fact that, as you say, Del is already debilitated and in pain and will not be relishing the thought of major surgery and of course you feel badly for him.
I know there are those on this site who have had to face what you're going through and I'm sure they'll be here soon to answer some of your questions and offer better support than I can give, in the meantime, I'm thinking of you, try and stay strong,
Brenda