Welcome, Rainy, so glad you found us! Though you're scared by the news, you're already forming your action plan to fight it, and I sense you will fight it on multiple fronts. I'll point you first toward our site Primer
It was written by physician member Stavia and is filled with explanatory and helpful information. I would venture to say it contains answers to questions you don't yet know you have.
I don't think you mentioned knowing about Dr. Dale Bredesen, and his recent book: The End of Alzheimer's: The First Program to Prevent and Reverse Cognitive Decline. Dr. Bredesen's ReCODE Protocol focuses on '36 holes in the roof' as it were, with suggestions to 'plug' those holes. Many on the site find the ReCODE program helpful (though not all work directly with Dr. Bredesen himself, of course).
Others on the site are followers of Dr. Steven Gundry, whose latest work is Plant Paradox. We have some members who see Dr. Gundry personally, and are kind enough to post information about their visits.
It seems you're ahead of the game, having focused on exercise and diet for a long time already. How are you at relaxing? Have you had lab testing recently (Vitamin D level; HbA1c level; hormone levels; thyroid testing; B12; homocysteine)?
We are always improving our site, and are developing Wikis. You can access those by clicking on the three stacked squares to the right of your name. At that same location, you'll find our site Search function. The total files on the site are voluminous, and there probably has been a thread on pretty much any topic you come up with.
A major plus for health is a supportive and understanding community - and that you have walked into here. Welcome again!