advice for disclosing diagnosis

My mom is 56 and was recently diagnosed with early on-set alz. She has always been a bright, bubbly, fun person, and she still is despite everything. The issue is that her main symptom is aphasia, and it's progressed to the point where she can't tell us much. She still tries to interact with people but just can't get the words out. At parties, it seems like she's drunk even though she isn't. (She was a charming conversationalist before, so aphasia is a big change for people who know her.) Her logic is also affected to the point that she can't drive, has trouble reading, can't text, takes a long time to figure out how to swipe a credit card, etc. She looks fantastic for her age and is very pretty, so if you didn't interact with her, you'd think there's nothing wrong. She doesn't want anyone to know because she still hasn't accepted that she has alzheimers, but it's very obvious that something isn't right when she speaks or tries to complete a task. Recently, her abilities have started to decline in a more obvious way.

My dad feels bad when he tells people what's going on because he feels like he's going behind her back, but I think he should tell more people. They're very involved in their church (small community), but he still hasn't said anything to the folks in their bible study class or other people who aren't family. I still don't know how much of our extended family knows. I've told my friends because I need the support, and I want my dad to get support from his friends/family/neighbors as well. Plus, I think it would help people better interact with my mom! I hate the idea that someone would think she was drinking or on drugs when really she's just doing her best to say what she can. And I know that there are friends who would come keep her company if they knew what was happening. I'm not talking about a big announcement or anything, but it just seems unfair to both of them to continue pretending everything's fine.

Has anyone else gone through this? How do you navigate telling people about LO's condition without hurting their feelings?