Made himself sick thinking about what they did to Laura?
That would require having more of a conscious than I believe he has.
2012 was a hot summer. If they killed Laura July 3/4 but didn't cremate her until July 23rd, there would have been a far bit of decomposition that occurred in between and the smell that greeted them when they went back to cremate her wouldn't have been pleasant. I suspect its more likely he's feeling ill from the memory of that odour.