Responses
http://www.mangago.me/read-manga/back_to_school/
umm It Wasn't Seme But It Was His Ex
Is That Ok?
It seems like you've read a lot so maybe it would be better to scroll through and see if there are any you haven't seen here?
http://www.mangago.me/tag/bully
I'm not really sure but good luck!
Can you please recommend me some manga where seme bullied or mistreated uke and regrets it afterwards? Something like hidoku shinaide or If you hate me so? Preferably completed