I feel for you.
Is it possible for your pdoc to write and to explain your situation? My pdoc did that with my insurer when they'd denied a med for me. He told them I do not fit their specific criteria; yet, it's his clinical judgment I'd needed the med and explained why. They then granted the authorization (for 3 years).
Oh, wait -- Is your pdoc gone? If so, *****!
Rexulti is mostly advertised for treatment-resistant MDD, and as an adjunct to antidepressants. (I have only seen 2 ads for Rexulti and BP Depression; I have seen many, many ads for use with MDD.
FWIW, Rexulti is now advertising to get the first month's supply for free. See their web site.
I hope this will work out for you! How frustrating!

WC