Why did Gulliver hate humans?

From the text:

My wife and family received me with great surprise and joy, because they concluded me certainly dead; but I must freely confess the sight of them filled me only with hatred, disgust, and contempt; and the more, by reflecting on the near alliance I had to them. For although, since my unfortunate exile from the Houyhnhnm country, I had compelled myself to tolerate the sight of Yahoos, and to converse with Don Pedro de Mendez, yet my memory and imagination were perpetually filled with the virtues and ideas of those exalted Houyhnhnms. And when I began to consider that, by copulating with one of the Yahoospecies I had become a parent of more, it struck me with the utmost shame, confusion, and horror.