Every Action Has An Equal and Opposite Reaction (Newton's Third Law.)

If this is the case, does gravity has an equal-opposing force?

From asking around I still haven't got a very clear answer; those who I've talked to seem to believe there isn't one - that gravity is actually a singularity [a one way force] which somehow "just works", others think it differently - believing there is an opposing force of which prevents gravity from compressing masses more than it already does.

So which one is the right answer? (if either!)