I'm an idiot! - help with Rally spindle nut

Converting my vector 3s over to Rally SPD-SL.

Eventually managed to find a socket that would fit. Like an idiot I put the nut on the wrong way round. Now the pedal will not turn and I can't get enough grip on the nut to undo it.

Any ideas? I could maybe drill the nut and hope to save the axle but would still need to find a new nut. Its the left pedal as well so I can't just use a standard pedal and drop down to single sided power