Does she realize what she is doing to her other children by having him in the house?
Well, I wouldn’t compare it to Sophie’s choice, since that was a Satanic - and utterly specious - proposition that the Nazi officer put to her - he wasn’t going to spare one child, he simply wanted to degrade and humiliate her even more by making her “choose” which of her children was going to die.
In this situation, the disturbed child is so miserable that being institutionalized is not going to be significantly worse for him, but his absence from the home could mean the beginning of a normal life for the other two children.
Thanks to the laws the ACLU got passed in the 70’s, it is now very difficult to get someone committed. They are actually expected to commit themselves!!!!