People Receive Text of a Party, Then are Brutally Murdered

by Abi
(England )

I'm searching for a horror movie that starts at a New Years party. Certain individuals receive a text telling them there's a better party on a different floor, they all go and there is a kind of treasure hunt until they all enter a room that is done-up like a child's party.

Each of the people there have a cake with a name on it, one of the names is "pig" I'm sure, and one by one they are brutally murdered. One kill scene includes a man being gutted and having the head of a pig on his...

In the end it turns out to be a female cookery presenter who was obese as a child and all these individuals had bullied her or hurt her in some way.
Please help me find the name of this film, its really doing my head in !!!

Thank you!