What your head?
This is indeed difficult to grasp. Actually at the center of a black hole spacetime has infinite curvature and matter is crushed to infinite density under the pull of infinite gravity. At a singularity, space and time cease to exist as we know them. The laws of physics as we know them break down at a singularity, so it's not really possible to envision something with infinite density and zero volume
Tie that and a few dozen other things to your infinite density and gravity in a zero volume, especially considering there was a pre-existing volume filled with that superdense particle.