I'm with everyone else on this one Louise, it's a sad thing to have to do, but I'd remove your 'friend' from your Facebook.
From the sound of things, she still is not over the loss of her boy, which is understandable and that is no reason to treat you in this way at all, but I guess, as others have said, grief is different for people.
She may be distancing herself from you as she is trying to block out memories of what happened to her boy and with Cameron's very unfortunate situation, it's quite close to home
For now at least, and a little sanity to you and your family, the only thing to do is try and ignore anything she has to say. And please try not to let everyone at the school get to you, they obviously don't understand the situation your in at present.
On a positive note, I'm so pleased to hear Cam's completed a full day in school, what a wonderful little boy - an inspiration to both other children and adults alike
Massive

to you all x x x x