Complex sentence: Liam becomes more hostile, and demands she show him the blank space on the "grain" where she erased it, but she no longer can hide the fact that she did in fact save that memory from 18 months ago.
Split into simpler sentences: Liam becomes more hostile, and demands she show him the blank space on the "grain" where she erased it. She no longer can hide the fact that she did in fact save that memory from 18 months ago.