Thank you for that. Though these matters are settled for me, I do enjoy kicking this ball around.
Although I accept for myself, based on my experience of my existence, that there are both a material realm and an immaterial realm that exist external to me, yet of which I am also a part, it is easier for me to imagine immateriality without materiality than the other possibility.
I have entertained the thought, though, that the only reality that I can know for sure exists is materiality, since in my experience of materiality I have a physical brain that I know could possibly generate all that I experience as immateriality.