fascinating indeed but as far as the identification of the self that would leed to the answer to do I exist I think can be found in something you said, "senses, that react with your brain." so, while your point after that is true that such senses are subject to alteration they must still be interpreted by the brain which proves that you must have a brain such that it is interpreting your existance. as far as your later point goes, on the posibility of a false reality, I could only hope that the life forms that might create such a simulation would be aware of the amount of sadness that they are cause to a large number of "intelegent creatures" so I could only hope we do not live in a simulation because if we do, our creators must lack any sympithy
wow, I got a bit dark there, my apologies