What is this movie and what's the name to it?

ok so it starts off with a bunch of people trapped in some big storm and all of them are looking for shelter. and there's this lady with her son and i guess she's still trying to get her son to warm up to her, so while she's fixing a flat in the storm the little kid backs up and smiles and she does the same. and then WHAM this other car hits her. then everyone gets into a hotel and there waiting for the storm to stop and then people start dieing. the lady that get's hit by the car get a bat shoved down her throat... and i'm not sure if it's another person but the people hear a thunk-ing sound in the dyer and there's somebody's head in there and then everyone talks and turns out they all have the same birthday and a bunch of other stuff. then every once and a while it cuts away from them and shows this big fat guy in court and stuff. well at the end the boy goes missing and detective guy dies but he saves the girl i think she was a prostitue or stripper. and like the guy's dieing words were live your life. and then it shows in a field i think and she's planting something and the boy comes out and says sluts don't get second chances and then she gets killed. then it cuts back to the guy and i think he says the same thing the little boy says and kills everyone in the car. turns out all those people were his multiple personalities and whoever survived took over his body. anyways i really like it but can't remember the name anyone know it?