Your purchase
agreement probably contains a clause telling you how to terminate
the agreement for breach by the contractor. Exercise it. You should
get your earnest money back with interest. However, you may not
be able to get consequential damages (moving expenses). If you
still want the condo, you might terminate the old purchase contract
and execute a new one, with a reduced price to cover your expenses
or a term specifying that the contractor has to pay you damages
if your mortgage goes above a certain rate.
