This is very sad to see. I looked at the account after seeing that and found several more similar accounts, either within the followers of this first account or within the followers of others. There are about 3-4 in total, all clearly revolving around the same purpose, namely supposed 'fan' accounts which are obviously designed for mockery and bullying, set up by Kate's then school peers. The peers in question look to have been the popular girl crowd, judging by the comments on the various posts.
For whatever negative points Kate may have, I do feel immensely sorry for her. Kids can be so cruel and clearly the mockery at school has had an impact on her. To be honest, it's probably a key part of the root cause surrounding Val/Mick's protectiveness of her and Kate's preference for OAPs.