Wait, so what I understood from the chapter is that she got hit by a shell, but somehow the MC was hypnotized by someone to think the aliens killed her, so that he could better accept her death. Is this correct?
The PTSD arc is the memest of all Alternative, but one thing the manga does well is to portray how miserable and despairing the characters involved are (saw the raws so believe me on this one).
The visual novel is rather tame in comparison, Takeru is coming out of this a wreck.