hiccup

we've hit our hiccup - we thought the appraisal for the house was already done and valued at the amount of our loan, but got word yesterday that we were mistaken... the appraisal came in significantly lower than the price of the home, so we now have to renegotiate the purchase price of the home. we basically have 2 outcomes:
     1. the seller agrees to the appraisal price and we get a lower mortgage payment
     2. the seller says 'piss off' and we have to start looking for a new house - 2 weeks before we're scheduled to close.
so - that's that. we're waiting from word back from our realtor to hear the seller's response. on pins and needles...