I was interested by this story, so I did some more googling, but as far as I can tell there are only two sources of information about the Cagots on the internet

I was interested by this story, so I did some more googling, but as far as I can tell there are only two sources of information about the Cagots on the internet. One is a widely copy-pasted article by the author Tom Knox promoting his book about despised peoples, and the other is the 1911 Encyclopaedia Britannica (https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Cagots https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britan...). Might be worth following up on the books cited in the Britannica article.