I can't remember much of anything to do with Shae, aside from Tyrion finding her in Tywin's bed after he was let out of the dungeons. I have the vague sense she may have testified against him when they were "investigating" the murder that got pinned on Tyrion, but that's about all I can remember, aside from the amount of trouble Tyrion went to over her because Tywin had that anti-prostitute fixation he had to work around. And with the murder subplot, so long as the show establishes Tyrion's supposed motive like the book did, blaming him still works.