It's not about 'C' anymore. It's mostly about K, and this has been very much apparent as far back as the first thread. Not only is this toxic, weak, easily-led woman thriving on your heartache @JaysusWept, she actively seems to be thinking of what things she can do to hurt you next. Since this whole debacle started, at least C has made no pretence of being anything other than what she is.
K is worst of this bunch by far. She needs dropping entirely, and fast, which will clip her wings nicely and cut off her oxygen supply of entertainment at your expense. The good news is that dropping you from WA was her last card. So now, unless you directly engage with her she has nowhere else left to go. Block every last one of them on Facebook. In the playground, smile and wave cheerily from a distance, without going near them. And if any of them approaches you, K particularly, pointedly put your earphones on and get your phone out, say 'got some urgent messages to check, excuse me!' (smiling all the while) then physically remove yourself from their presence, burying your nose in your phone as you go.
It IS possible to make it all go away, despite short-term gossip which will be like yesterday's chip-paper in all of a few weeks. 9 times out of 10, the other parents won't care less. I also wouldn't mind betting they already have these people pegged as the 'playground clique', and the full extent of their engagement is to watch with wry amusement as it implodes, as cliques are wont to do.
You are so much better off out of this melee, OP. Dutch courage and 
for the school drop-off/pick-up today.