If there’s no situational cause for this change in behavior, there’s a chance she’s experiencing paranoia from an undiagnosed mental health condition. Look up the signs of mania (bipolar disorder), borderline personality disorder, and schizophrenia. If it looks like it might be one of those then you need consult professionals and family because it’s not something you’re going to be able to help her with on your own with advice from Internet strangers.
Take care of yourself, of she continues to behave abusively you need to get away whether this behavior comes from untreated illness or not.