I don't know. Billie seems like someone who would fight back if pushed into a corner. I don't think she'll turn right now, but if SA tries hard to push this whole thing on her, I don't think she'll just take it all to save him. Billie is all about herself and her feelings. I don't ultimately think she would go down for him for a crime, but I guess we'll have to wait and see.
I wonder if she's the one who did this and maybe SA just got rid of the body for her. Her control over him and willingness to cover for him in the past is more than just love to me. And he has never done the same for her.