Alive99, you've "hit so many nails on the head"!
For whatever reason, it's easy to just soak everything up like a sponge. Even sponges reach their limits. In my case, the wakening moment can be when you realise that the person saying thank you has an alternate agenda of emotional blackmail. The disappointment that the person who supposedly taught you right from wrong is now advocating an unacceptable resolution to a family problem.
RDMercer, I can relate to how your wife is feeling. Whether it's illness or old age, the inability to do tasks can lower self-esteem. That's where a lot of my mother's problems lie. Is there an opportunity for you to just sit with your wife for a chat? Subjects other than her illness or your wish for validation. Saying to lighten the mood may seem flippant but it could be a good starting point to address the more serious issues later.