You seem to think defederation is taking a stand against something that is wrong, but defederation is really closing your eyes and ears pretending what you don't like is not out there at all. I fail to see how this is better than doing nothing.
Besides I bet they are going to love that other instances defederate from them, they will just say it proves their point how they are the good guys and everybody just wants to censor them and hates them for who they are. I fail to understand why you would give them that
I have a friend who was in similar situation.
Your wife does not decide if you need medicine or not. Doctors do. I don't know if you should take your meds in secret or right in front of her, you should do whatever you think is best for you in this situation, but you need to be taking your meds.
What helped me convince some people that ADHD is not a made up problem was the pictures on Wikipedia's ADHD entry (in Polish) showing some difference on PET scans of regular person brain and ADHD brain. Showing people that and saying there's literally a difference in a brain you can actually see made them think twice