In a real estate contract what is considered diligence by buyer?

Generally when you sign an offer to purchse a house it will include piece on conditions. Most offers to purchase are conditional on finances. So that way if you cannot obtain fianances the offer becomes null and void and you get your deposit back. I would check your offer to purchse the house for this phrase. I would still consult your lawyer, this is part of his job since the contract may be broken.