I still don't totally believe her--
I don't think she believed the immunity deal would save her if Lizzie died because of her, or because of both of them so she stuck it all on Seth and played just a bit part. I noticed how there seemed to be no conversation between her and Seth as or just after he strangled Lizze, she just quietly walked to the window, closed the drapes, he gestured for her to close the other drapes, she went to the bathroom - why in the world didn't she at least ask him why are you killing her????