ADHD partner no longer “the problem “

My partner who was already diagnosed as a child has now after 20 years together decided that he is no longer the problem. It's me, it is all me and my high standards and expectations. 
This is the new them and they demand to be accepted as is. They are done believing that ADHD is causing our issues and it is now time for me to put in the effort to change and accept. 

I am angry, I am bitter, I am frustrated, resentful and furious. Not a slither of my old joyful self is left and they firmly believe they had nothing to do with that. 
What's next? Anybody else experienced such a shift?