Montag realizes that his whole life had been such a facade that he explains he would feel what If his wife was to overdose to death tonight?

From the text:

And he remembered thinking then that if she died, he was certain he wouldn't cry. For it would be the dying of an unknown, a street face, a newspaper image, and it was suddenly so very wrong that he had begun to cry, not at death but at the thought of not crying at death, a silly empty man near a silly empty woman, while the hungry snake made her still more empty.