Question on "The Forged Origins of the New Testament" and Josephus

Does anyone have an apologetic response to this website? [The forged origins of the New Testament](https://www.bibliotecapleyades.net/biblianazar/esp_biblianazar_40.htm) Basically, here the author claims that Constantine gathered up all the manuscripts and burned all but a select group, and had Eusebius amalgamate the "'legendary tales of all the religious doctrines of the world together as one', using the standard god-myths from the presbyters' manuscripts as his exemplars" based on ideas behind Caesar, Krishna, Mithra, Horus and Zeus. **UPDATE:** Please note that related to the above my friend says that you can't even prove that Jesus existed, was crucified and rose again from the dead, so I mentioned the work of Josephus. His retort is that the works of Josephus have been corrupted. Does anyone know, is this true or not? When I search this site I don't find any information on the historical accuracy of Josephus (see https://christianity.stackexchange.com/questions/20584/how-do-christian-theologians-view-and-or-use-jewish-commentators) .