You previously said she’s unable to handle day to day tasks independently and is fully dependent on others for basic day to day living. This is extreme case for a 50 year old woman regardless of her disorders.
What’s the chance that all of a sudden she’ll get a job and start contributing if she can’t even handle regular daily living.
I think you need to prepare yourself to what is to come. You are approaching retirement age and you are taking on a dependent adult now whom you barely know. Of course that’s all a moot point as she’s married, but just hypothetical.
But if she leaves, and moves in with you…You might have to work all into old age as you’ll have to support her now.