the epoxy will never cure unfortunately it is the wrong type of chemical reaction you are best to strip it all off now clean up the mess and start a fresh. I made a similar mistake on my first surfboard i made! you will only do it once. I make sure i always zero the scales before adding the hardener as it saves simple mistakes. The other time this can happen is if you do not mix the two parts well enuff but sounds like you know were the problem came from.