I'd change the oil for good luck and to see if there is any coolant in the old oil. You could do a compression and or a leak down test.My guess is the worst thing you might have done would be to warp the head or blow a head gasket .But My guess is that if you still had all your coolant that you did no damage.I think that the one belt system that most if not all car makers use is one of the worst designs possible .......

William Rogers........