Recent MCI with Alzheimer's diagnosis for my (54 yr old) husband

I am at a loss for words, how to feel or "knowing" what to expect. I've "known" something was off the last 4-5 years, but he would blame his forgetfulness on stress and the busyness of our lives. Our kids now range 12-16 years old. But the last couple years there have been significant changes in his memory, spatial distancing (car accident), navigation is constantly on for familiar places, not knowing what day or month it is.

We have an appointment with his neurologist tomorrow to go over his genetic markers (APO E4) to see if he's a candidate for the immunotherapy offered. I am now appointed as his caregiver so I have access to his doctors without HIPPA getting in the way.

He's still working and driving. We told his parents but haven't told the kids yet. We don't share too much with his parents right now because they are going through their own terminal illnesses. I feel so isolated because not only have I never known anyone personally to go through this, but I can't talk to any friends about this (respecting his wishes) and also just so saddened because he is "young" for this disease; not to mention grieving growing old together. I would appreciate any suggestions regarding questions to ask his neuro, tips on how you worked through this and anything you'd like to share. I am open to any kind of support. I am at such a loss right now.