I'm one of the posters who believes she saw a reference to Olga retreating into the linen closet and vomiting into a towel. Since that time I have been unable to find the reference. Given Olga's sensibilities and the nature of the work she, her mother and sister were exposed to, I think it highly probable such a thing could have happened; nonetheless, until it can be documented I would not want to say that it did.
If I recall correctly--someone verify this, please?!--Alexandra mentions Olga taking arsenic in the course of her correspondence to Nicholas . . . NOT as poison, but what was at the time thought as a curative for anemia and the resultant physical/emotional lethargy, as Sarushka mentions.
As for what Tatiana and Olga saw, you have to remember that the longer we live, and unless we live very sheltered lives, we are likely to witness sad, possibly horrifying things. Particularly when the world is volatile, as it was then and as it is now.
P.S. Sorry FA, only just now saw your post!