Dave,
I don't think it is important that we don't know each other or that I may only be an interested party in aviation, what qualifies me to write this note is my deep respect for you and other instructors who have chosen to share a beautiful and hard earned skill with those of us who want so much to be . What should give you pride is the amount of students turned over in the years you have taught who are safe, capable pilots.
I am sorry for your injuries, and the pain this will also cause your family but you can adjust and adapt to overcome this obstacle in your life.It was not long ago that I read an interesting article about a Harrier pilot who was paralysed in an accident but who fought the FAA an more importantly the CAA to gain his CPL in a specially adapted a/c. You can achieve anything when your focused on it enough. Good Luck sir!