I don’t think I need to spend much time on infinity. Infinitus est numerus stultorum. It suffices to point out that you cannot show me infinity of anything whatsoever. Since everything is finite, including every number, putting them all together will still not get you to infinity. According to math (and also its feisty sidekick, the English language), the number before infinity would be known as the “penultimate” in the series of all numbers. So in my opinion, the last number in the number line is the penultimate.
There is also a convenient common sense method for refuting infinity. If there were infinite numbers, then the Universe couldn’t fit them all in. But clearly the Universe does fit them all in, by the transitive property. It fits our brains, and our brains fit all the numbers. Please see William Lane Craig on this point, for further discussion.