Get category then sort by meta-value

I have an Obituaries page where I would like to list an archive of the posts in that category, separated out by year.
So I figure I want to get posts where category_name=obituaries
THEN, get all the values of meta_key=obit_year
THEN, foreach obit_year echo the obit_year
Then, loop through the posts

I’ve looked a many examples of code, but I’m stumped practically right at the start – how structure the query within the query.

(Obit posts are not always going to come in on a timely basis, so I can’t rely on the post date for sorting).

Thanks for any pointers
JA