Chapter 75 of the uncut version did it for me. It has messed with my emotions.
After all the horror, death, and chaos, it wasn’t the monsters or the battles that broke me. It was a little Christmas tree in the snow. It was Tom Cullen, holding presents wrapped in wedding paper, singing "The First Noel" off-key (I even searched the song on YouTube and listened to it while reading, and man, it hit), and Stu just quietly watching him with love.