What kind of wasp? is this...it was huge!?

That is awful big but it sounds like what is commonly called a dirt-dauber for the way it builds small mound shaped closed tunnes to deposit their eggs, I have never heard of one stinging any one and they are not easily agigatated but I'm sure they could, I has see them fight other wasps.

To correct Nomadd, the common name of this species of wasp is the Tarantula Hawk, not the Tarantula Wasp. It has a weird way of taking care of its young.

Tarantula Hawks will find a tarantula or other large spider and sting it with a powerful toxin that paralyzes, but does not kill the spider. The tarantula hawk will then drag the still alive but paralyzed tarantula to its nest, where it will lay a single egg on top of the tarantula. when the egg hatches, the still living spider becomes the newborns first meal. It will eat the spider alive.

Seems cruel, but its the way of nature.

That's a tarantula wasp. They sting Tarantulas and drag them back to their hole.