Sorry for the late response my notifs got drowned
Any of these?
https://www.mangago.me/read-manga/bitten_by_the_dog_i_abandoned/
https://www.mangago.me/read-manga/i_tamed_my_ex_husband_s_mad_dog/
Thank you do much for your help. I finally found it, I came across it on tiktok. Here is the link and thank you.
https://www.mangago.me/read-manga/if_you_wish_for_my_despair/
All I remember is that the fl (mc) is forced to be engaged with the ml who hates her because her family, I think killed his parents. So he neglects her and then later on she falls in love with someone else. Everyone, including the ml knows that because they are openly dating. So, the ml sends him to war and he never comes back. This leads the fl to hate the ml and says that she will kill whoever he loves so he can feel the pain she feels.
I'm not sure what happens next or the description of the characters. Someone help me find it, I have been looking for it.