Cold hardiness depends on the species. Can you post a photo?

I'm hoping someone else might be able to identify it for you...I know cold hardiness varies, but there are only a couple of Opuntia species I can recognize. You could also try looking through the 181 species here, though many look quite similar: http://cactiguide.com/cactus/?genus=Opuntia

That looks like something from Brazil, I think, and therefore would not be cold-hardy, even in the mild-cold of Georgia. It will grow wonderfully outside in the spring/summer, as long as it has good drainage from winter rains.

It might be one of the tropical species. Or it might be a stretched Opuntia ficus-indica, which can tolerate light freezes. Best to bring it inside during cold spells to be safe. Also keep it very dry, especially in that rich organic soil (something more gravelly would be better). Next year you could root one of its pads to have a second plant to experiment with.