Assuming that the person who you shared the room with won't come back for verification AND if you somehow feel bad about the whole affair, just donate the refund to your favourite charity!
She did donate the refund to her favorite charity... her credit card. Just kidding, that was too good of a setup to pass up...
OP mentioned being on disability, perhaps there was something about the room that was difficult to use/access (perhaps OP requested a wheelchair accessible room and rec'd a standard room or something to that effect).