Sort of. They were predicted by Einstein theories. But in a way so absurd that it was supposed to be just a faulty part of the theory when you push it to a extreme. Basically the "infinite collapse" that occurs and that should put all mass in a infinitely small space.

That cannot be true, it collides with quantum theory.

We have observed the space surrounding black holes, and that is spot on with the theory. But we know nothing about what occurs inside them. We don't know the density of the singularity, it's structure, how that matter behaves at quantum levels. We know nothing about that.

Once you enter a black hole is not only that you would be torn to pieces and pieces to atoms, we don't even know if atom structure would even exist in there. Maybe even boson-fermion structure doesn't even exist inside a black hole.