We know black holes exist.
Theoretically... unless you have pictures of one for me.
We seen them, indirectly though other em bandwidth, and with hawking radiation. We know they exist from the mass they exert with their gravitational affect. We know each active galaxy mass and energy ejection is from a black hole We know that each galaxy has a huge black hole in the center it, and with black holes and dark matter, and dark energy halo is required for galaxy formation. Its theoretical in the sense of gravity. They're proven beyond doubt.
Yes, the singularity at it center escapes us. Our physics is good at super large and heavy things and super light and small things. Not with super small super heavy thing. That however doesn't preclude it from existence.
Ugh, guesses on guesses. Do you have a little formula on you that states exactly how light is affected by gravity, energy, and other light? Hell, we could just be matter that interacts with other energy causing it to deflect as if it were matter. We don't know enough about the situation and everything you read about it is a theory based on the of perceived behaviors of light, gravity, and energy (which could all be the same thing...)
That's why everyone is so interested to find out what's at the middle. If it's nothing, the black holes you are referring to are cells of energy being deflected or accelerated beyond the speed of light (which is another theorized limitation that we cannot prove and base all our estimations about black holes on.)
For all we know, Einstein was wrong. He's been proven wrong about parts of his theories. There could be energy or objects out there capable of super-light speeds. Just as we have in the past, we are formulating the best answer for the data we know. The Earth is flat, etc.