HiDee Brother Johnnie..I woke up at 5AM today, since this Initial Question of "Does 'Nothing' Exist" has a rather simple answer, JMO.

Your initial premise "'Empty Black Space' IS Something" for-starters isn't true. It's a nice Verbal Description OF 'Nothing'..but just because you CAN describe it doesn't De-Validate it's Existence.

Matter-of-Fact: "Most matter IS empty space"..so there's really a LOT of "Nothing" to go-around (Even AFTER the Singularity Popped..13.7 Billion years ago..& "Something" became reality.)

"Deep space is 4 degrees above absolute zero" means, yeah, there's SOMETHING (atoms, for sure) In-Between all the NOTHING out there..but that's very FEW of those Somethings, & Temperature's-Taken over a period of TIME. (So at any given instant, I'd argue there's NOTHING to BE measured..SOME of the TIME.)

Oh, and that's using just the 4 Dimensions we know much about. (We still know Next-to-NOTHING about the Others we're discovering..Or WHY we're blessed..or maybe cursed..with all this SOMETHING-Ness...)

Your Fellow MugWump,
Stan