Welcome to the bewildering world of NMD! I'm so sorry about your diagnosis, noticeable decline, and the constant pain. The pain must be especially hard to deal with and certainly contemplating being reduced to a purely existential state is the biggest challenge of all.
Amazingly though, the cruelties, challenges, robbing of functionality, etc. that this disease throws at PALS has the potential to teach both PALS and CALS to enter a whole new dimension in their lives which offers a much more reflective way of daily living devoid of some of the superficialities that keep us captive and blind us to what's really important.
I hope your wife can soon come to terms with your illness and be there with you in the truest sense. She sounds as if she's fighting your illness as much as she can which will ultimately make it so much more difficult for her. You're really going to need her and I hope she soon can enter the world you're living in now and be there for you.
I thought that the words written above by Robert Mathis were so helpful and inspiring where he said "to keep going, I have found it very helpful to make plans for the future and to work toward fulfilling those plans. ALS is a terrifying disease if you spend too much time thinking about it. So I focus on the things that I can do and try to be as positive as I can." (Thanks Robert!) I hope you can heed them. You sound as if you are able to have a similar outlook when you say "I try to set achievable goals every day that require some effort beyond myself - something that exists, if only briefly outside myself. If I can do that, it's a good day regardless of anything else."
My PALS husband is really experiencing some significant losses now (speech, walking ability, swallowing ability) which are so difficult to come to terms with. I would hope he could heed those words too.
All the best to you and be sure and keep participating in this forum. So many are travelling this journey right now and we can all keep in touch and help each other through our daily struggle.