I am so sorry you are in such pain. I am new to this forum so I am sorry I do not know your story, but I wanted to express my concern
I do know how you feel. I have been disabled since 2000. My husband hurt just as badly as I did. And as you said, it is so hard knowing I was the cause for his pain. I often said the first thing I felt every morning was pain, the second thing,,,, guilt.
My husband now has Alzheimer's disease. I am now his full time care giver.
It is extremely hard, but on bad days, all I have to do is think about how lovingly he use to take care of me...and know that he still would today if he was able.
Having now seen it from both sides, I emplore you to let go of the guilt. I know see why my husband hurt so badly seeing me suffer, just as your wife does. The only reason we hurt, is because we love so much. Allow her to love you, to help you. It is hard, but there has been no greater gift than being able to care for my husband. I am sure your wife feels the same way.