The 18' driveway is where? Along the right side of this drawing?
Is this property you're selling a separate parcel, already recorded as such, from your house, barn & pastures? Was it bought as 2 properties adjoining or are you subdividing? An easement, instead of either ownership OR a deeded tight of way, isn't always agreeable for a bank loan.
Depending on the writing of the original contract & extension, AND if any changes or addendums added, you may very well be able to cancel. Do that if you can and get all your paperwork & recordings squared away. Then remarket it.