Repulsion and Space

According to Kant, in the Metaphysical Foundations of Natural Science, "matter fills its space by the repulsive forces of all its parts."  That matter "fills its space" follows from his doctrine that infinitely divisible Space is given a priori to any such phenomenon.  However, Repulsion effects a process of separation, and a process of separation opens up a gap between what it separates.  Hence, Repulsion fills a presumed a priori given space by creating a space a posteriori.  Thus, Kant's concept of Repulsion seems to present a formidable challenge to his theory of Space.