This situation sounds really awful, I´m sorry that you have to experience this. Such info must of course be the worst you could hear from a T, that he or she is severly ill, I can´t imagine what that would make me feel.

I think your reaction is perfectly normal, I would perhaps also take some kind of flight and I´m now not saying this in a negative way. You sometimes hear about relatives of a sick person who chooses to not be around when his or her sick relative is very ill and you don´t know if they´re going to make it or not.

Even if a T isn´t your relative the feelings are quite the same as the relationship itself is often very strong, especially as you´ve seen this T for 12 years.

I really advice you to contact your T if you feel the decision to end therapy with her was wrong. Perhaps it´s better to be with her as long as you can and as long as she manages to meet for sessions. I would say to her that I just want to be with her and of course you have to talk but perhaps in a less intense way because of the state she´s in. If the T herself accepts this I would try to stay in therapy even if I of course think ending therapy should still be an option if you feel that´s a better solution for you.