Black holes
Strictly speaking, black holes do not exist. Moreover, holes, of any kind, do not exist. You can talk about holes of course. For instance you can say: "there is a hole in the wall". You can give many details of the hole: it is big, it is round-shaped, light comes in through it. Even perhaps the hole could be such that you can go through it to the outside. But we are sure that you do not think that there is a thing made out of nothingness in the wall. Certainly not. To talk about the hole is an indirect way of talking about the wall. What really exists is the wall. The wall is made out of bricks, atoms, protons and leptons, whatever. To say that there is a hole in the wall is just to say that the wall has certain topology, a topology such that not every closed curve on the surface of the wall can be continously contracted to a single point. The hole is not a thing. The hole is a property of the wall.
Let us come back to black holes. What are we talking about when we talk about black holes? Space-time. What is space-time?
Space-time is the ontological sum of all events of all things.
A thing is an individual endowned with physical properties. An event is a change in the properties of a thing. An ontological sum is an aggregation of things or physical properties, i.e. a physical entity or an emergent property. An ontological sum should be not confused with a set, which is a mathematical construct and has only mathematical (i.e. fictional) properties.
Everything that has happened, everything that happens, everything that will happen, is just an element, a "point", of space-time. Space-time is not a thing, it is just the relational property of all things.