Word "if" means, that I am assuming the HC existence. No assumptions are in the proof. I am considering an imagination. Then the latter becomes real.
Consider the person HC, who knows ALL Reality. Then He knows own existence, because we considering Him. Thus, among ALL Reality is the existence of the HC.
This is merely using fraudulent, circular logic. You are assuming your conclusion in your premise. You can see this easily because you can replace "HC" wth "the boogy man" and you still get to the same place.
You are falling for the same faulty logic as St. Anselm did. Anselm defined God as "that than which nothing greater can be thought", and argued that this being must exist in the mind, even in the mind of the person who denies the existence of God. He suggested that, if the greatest possible being exists in the mind, it must also exist in reality. If it only exists in the mind, then an even greater being must be possible—one which exists both in the mind and in reality. Therefore, this greatest possible being must exist in reality.
Anselm was obviously wrong, using nothing but a faulty, dishonest logical fallacy. It is nothing but an exercise in circular reasoning, as he, like you, was using a man-made definition of God.
In short, you cannot use a definition of God that assumes God exists and expect that to count as evidence for God's existence. It is beyond ignorant.