Why would Molly's friends friends turn on her and eventually bully her? I think that Molly's friends did that because they didn't want to be known as the friend of the blind kid. They didn't want to have to help her get around or be nice because then the same thing could have happened to them and then they would have become the kids being bullied. Or maybe the turned on her and bullied her because they didn't want to be friends anymore and with everything else going on in her life they thought that she wouldn't care and that everybody else would give her sympathy.
Should Molly's mom have told the school about the incident in the forest? I think that it was the right choice not to because then if Molly went back to that school then she could have been bullied even more because she was getting special treatment from the principle.