The I does exist in the very broadest sense, because human beings perceive it and allow it to inform a great deal of our behavior. This is almost as important to acknowledge as that the I doesn't exist in the sense it is presented to us by the I itself, which I believe is the point you're trying to make. It is impossible to propagate this in an agentic sense. You can't just go out and ask people to ask themselves if they really exist, because as narrated by the I, the I not only exists but is almost invariably the most important part of the organism (this is probably what you mean when you use the Freudian notion of the ego throwing up defenses).
Try to extract some of those terms you're using from the soup they're flopping around in and really inspect them. For instance, the ego was fundamentally developed around a Cartesian idea of the self and is probably not a good word to use because it implies the existence of a 'true' self. You could modify your definition of ego to fit the bill, but then your ability to propagate your idea to others falls to nearly nothing because of conflicting term definitions. You need to develop a positive alternative to the self.
Until you are ready to get into an objective debate about this, which will take a lot of effort and thinking, you won't get far and will likely grow frustrated eventually. Only on solid ground in the objective can one ever hope to make sense of the subjective. In this case, biology is that objective ground: without understanding the body, the nerve system and its connections and communications, you can't possibly hope to show that the way our internal narrator presents the world is an illusion, less still can you hope to show how it does it.