God is acting upon nothing
out of His omnipotent power.
You are aware that the standard model of cosmology (Friedman-Lemaître model) actually relies itself, ultimately, on creation ex nihilo.
Friedmann–Lemaître–Robertson–Walker metric - Wikipedia
The standard Big Bang model, as the Friedman-Lemaître model came to be called, describes a universe which is not eternal in the past, but which came into being a finite time ago. Moreover, –and this deserves underscoring–the origin it posits is an absolute origin
ex nihilo. For not only all matter and energy, but space and time themselves come into being at the initial cosmological singularity.
As John Barrow and Frank Tipler emphasize, “At this singularity, space and time came into existence; literally nothing existed before the singularity, so, if the Universe originated at such a singularity, we would truly have a creation
ex nihilo.”On the standard model the universe originates
ex nihilo in the sense that at the initial singularity it is true that
There is no earlier space-time point or it is false that
Something existed prior to the singularity.
Today, few cosmologists doubt that the universe, at least as we know it, did have an origin at a finite moment in the past. The alternative—that the universe has always existed in one form or another—runs into a rather basic paradox. The sun and stars cannot keep burning forever: sooner or later they will run out of fuel and die.
The same is true of all irreversible physical processes; the stock of energy available in the universe to drive them is finite, and cannot last for eternity. This is an example of the so-called second law of thermodynamics, which, applied to the entire cosmos, predicts that it is stuck on a one-way slide of degeneration and decay towards a final state of maximum entropy, or disorder. As this final state has not yet been reached, it follows that the universe cannot have existed for an infinite time.
Modern day physics indicates that the universe is
not going to eventually contract in upon itself, but that space will continue to exponentially expand, and the universe will eventually find itself in a cold death.
My point in saying all that is while you might not personally be able to comprehend creation
ex nihilo, it is the reigning model among cosmologists (not just Theists).
There is nothing logically contradicting about creation ex nihilo, nothing you've said would actually suggest that there is. If you think it is not possible, you should take it up with modern day physicists.
Some of the above was pulled from an article by someone I'm sure you respect greatly.