In Bohemian Rhapsody (2018), Queen is discussing about Roger's car song in the upcoming album, which is about to release:

Freddie: We could all murder each other...but then who would be left to record this album?

John Deacon: Statistically speaking, most bands don't fail, they break up.

Freddie: Why the hell would you say something like that? Roger, there's only room in this band for one hysterical queen.

What does "one hysterical queen" refer to?