AO3 has a very good tagging system, although this niche isn't super popular on there. There's a couple of folks on hentai-foundry cranking out good smut as well.

I'm also a big fan of CHYOA, although there aren't a ton of stories on there that feature this fetish.

There's a story that I'm having a little trouble finding again. The gist is that a mother is forced into prostitution in a foreign country (I think Vietnam?) and the son has to listen in an adjoining room while the disgusting landlord pimps her out. It hits similar themes as Almost Gone Forever by  Anal_King, except the crucial bit is that it ends with the son escaping and leaving his mother behind and ends up seeing a video of her years later. Thanks!