"I will build" is obviously what He said, although I grant it was not spoken in English nor in Greek.
And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.
-- Matthew, catholic chapter sixteen, protestant verses eighteen and nineteen, as authorized by King James
How many times to Catholics have to be shown the difference between Petra and Petros to finally get it? Even the church fathers and the Catholic Church itself say it was on Peter’s confession.