Depending on what you think is ‘toxic’ specifically in BL/Yaoi (because let’s be real it’s normal to see possessive tops and non consensual shit because its FICTION) you may find something you like here (btw it’s other people’s list, I can’t fully remember the ones I’ve read nor have the patience to go through my read mangas):
https://www.mangago.zone/home/mangalist/890642/
https://www.mangago.zone/home/mangalist/92280/?filter=&page=2
Here’s some tags:
https://www.mangago.zone/tag/unhealthy+relationship/
https://www.mangago.zone/tag/bad+seme/
https://www.mangago.zone/tag/toxic+seme/
Just filter through. Have fun!

Ugh I love toxic troupes (IN FICTION LEMME SPECIFY) because most of the time in the end they won’t exactly say I love you but they will murder for you.