How do you stop yourself going totally insane???

My baby girl that used to be so good is pushing all my buttons and i think i might jsut go insane!
Regressing in TTing, MAJOR MAJOR procrastination at bedtimes and getting dressed. I can deal with the "but why?" however the answer of "because" to everything i ask might just do my head in!!
seriously - i know this will pass but in the meantime....