Reaction to the death SPOILERS

Since thank goodness I never had anyone close to me die, or see a genuine reaction to sudden death (again, I consider myself lucky obviously) so I have no way of telling whether this question is justified. But.
When the poor kid gets shot, the mother's first reaction is to switch off the telly. No crying, no screaming the kid's name, no crawling to the husband, not even after she "breaks free", when her biggest concern is putting on some clothes. Very practical thinking, I have to admit. Then again, generally in other films they spend a little more time grieving, sometimes they spend entire films dealing with grief.
Tim Roth's reaction at that point seemed a lot more realistic to me and believable in terms of what a person would behave like if their son was just shot in the face (not to mention the rest of the situation).
Or maybe she was just that strong, or the adrenaline, or she was hyperrealistic (although I strongly doubt that since for the rest of the film she didn't do much).