The short answer is: read your contract or consult a qualified attorney .
Usually there are provisions in each contract that allow the buyer to back out of the deal without any penalty like giving up their earnest money or other fees paid in advance. Not being able to secure financing could be one of them. However, I have never seen a contract in real estate where change of heart or mind was considered acceptable for that purpose.
I do not suggest you stop your payment even though I don't know the details of your case. That could expose you to further loss due to breaking contract unilaterally. If you can not use the contracts provision to back out, communicate with the seller (perhaps through your agents)and try to come up with an amiable solution. Worst case senario, if your payment make you really uncomfortable and worried, cancel the contract appropriately, give up your earnest money and avoid further financial loss and troubles in the future. If you are not really in trouble and can make those payments without losing sleep on it, go ahead with your original deal and enjoy your new house. Please note that I am a real estate agent practicing in Woodbury, Minnesota and have no qualification or authorization to provide legal advice to anyone.
I hope this can help and please read your contract and be clear about your financial obligations and commitments in detail before you sign any contract. Good luck to you.