spoiler: dont read this if you didn't play the game yet:
for people who didn't get it.
in chapter 2 jack explains he uses some kind of drug. When he uses a overdose its possible he will do things he dont want to do and later on dont remember them.
So in chapter 5 he have taken this overdose. So in the final level he kills caithlyn, and shortly after that he don't remember doing so.
thats when the company of myself is set in place.
remember that all levels are inside caithlyns (or jacks) mind. Only the things that happens like the talking of people are real. Chapter 5 (the meadow) stands for a place caithlyn sees because see is happy because her sister dumbed that asshole thomas and jack haves this place in his mind because of the overdose of drugs.