I really need to find this because it has been bothering my mind for 3 days straight
And I cannot sleep because it stays on my mind (╥﹏╥)
I beg of youu if you even have a story that comes to mind, even if its just a little bit similar because I'm not sure about the details I wrote here
It's not it, but I managed to find it after skimming through the genre supernatural!
Thank youu for your help! ༼ つ ◕‿◕ ༽つ
Its this
https://www.mangago.me/read-manga/the_evil_god_descends_i_own_great_hell/
All I know is that he regressed back in time before the apocalypse begun? If remember correctly he died because of his girlfriend, not by her hand though. Not sure if he has a sister, I also know that their family possess a great power or so, I think it was a wood with some writing, this opens a gate. This gate is full of demons? Or monsters, I can't remember. But I know that he can also come in contact with the girl who kinda manages it. I'm not sure if it was modern, semi-modern, or historical but I'm guessing its the second one. Not sure if it was a manhwa or manhua, I think its the latter