That our Universe is a very big black hole article:
Are We Living in a Black Hole?
And why our Universe has not yet collapsed in a singularity is explained here:
Our universe resides in the center of a black hole, this theory claims
Black holes are generally produced by stars that are spinning. Like a skater pulling her arms in a spin, a star collapsing into a black hole spins at ever faster speed.
Rotational speed could approach the speed of light and in a very small radius, that's enormous centrifugal force (pardon my layman's term) that may be sufficient to counteract gravity, (not to mention other forces that may contribute to counteracting gravity). Which is why some scientists believe why singularities would not form.
And in the case of Universe, would be necessary to allow for evolution of matter or even life / living entities inside the black hole.