Whatever exists for you, exists for you. Whatever is outside your perception and experience, simply does not exist in any meaningful way. Perhaps (and most likely, imo) "it" (whatever "it" is) exists independently of your own being, but insofar as you do not perceive it, then it is nothing more, or less, than "dark matter": the unknown, and unknowable.
Such is the thrust of quantum mechanics (insofar as physical science is concerned), and such is the bane of finite being (insofar as existentialism in concerned)...and the source of endless and purposeless discussions about "reality."
For example, when and if "God" talks with me, then It will become a reality in my life. Otherwise, It's just a figment of my imagination {translate: a psychological product of my social upbringing and environment).
Bottom line: I will never know, and what's more, can never know.
And so now I do believe I will simply enjoy a latte (which I can taste), and look at the blue morning sky (which I can see), take a deep breath of fresh air (which I can experience), and give Kate a big hug (which I can feel)...and then off to work (which I can hate LOL).
Craig