How do you deal with an 'on the way out' pet?

I did think about just releasing her into the forest. She is a totally indoor cat. That is why she made 19. Outdoor cats don't live long here. Anyway, releasing her seems cruel, but on the other hand it could be a last taste of freedom. It's tough to reason this out.

if shes lived her whole life indoors i doubt she would want to die in the great outdoors
does she get temped to go outside when you leave the door open?