Driveshaft/CV Removal

You need a multi point socket and get someone to put the footbrake on while you undo it with a big bar
What should of done is undone it when the wheel on the car and on the floor
 
Put the wheel back on without the centre cap, and put the car back on the ground with the handbrake firmly applied, before trying to undo that nut.

you'll need a BIG breaker bar, and a suitable socket. I use a 2ft bar with a length of scaffolding tube over the end.
 
you need a 30mm 12 sided socket