I felt this about Madame T. I spent three months with her working on it. It was some of the best therapy work I've ever done.

I faced my feelings and made a plan.

You might want to ask your T:
1. How would I find out if you died?
2. Would I be welcome at the funeral?

You can talk about her dying without triggered her over getting old. The "traffic accident" scenario is perfect in this respect.

PS:

At one point I feared that if I went to Australia on business, she would die. She would live if I didn't go.