Other than being completely beside herself with worry, a diagnosis of ovarian cancer, potentially bladder cancer, I doubt the bladder has anything to do with cognitive ability.
No, they don't take the bladder out when they do the TURB. They will remove the tumor, hopefully, get good margins around the tumor and get it biopsied.
The pathology evaluation will be to determine stage and grade. Then they will talk about treatment plan.
Ovarian cancer is pretty darn serious also.
Unless there was some other analysis you didn't mention, you don't know that she has bladder cancer yet. She has a 5cm bladder tumor. The pathology will indicate if it is indeed cancer. Hopefully, it is a low grade bladder cancer, in which case they will most likely just remove the tumor and then take a 'watchful waiting' approach to see if it comes back.
That will allow them to focus on the ovarian cancer.
Hope all goes well.
Mike