Please Help Me Find This Manga

I read this manga like years ago but I can’t remember the name or plot all I remember is that there was a age gap and in one of the first chapters the FL’s flip flop broke and older ML fixes it for her

Help find BL webtoon
The MC accidentally witnesses a murder and in panic, told the murderer that he likes him (and that he is a stalker?)
The murderer is actually a hitman I believe, and works as a veterinarian. (He also has a sister who is in the same business?) Very handsome
So basically MC pretends to be madly in love in order to stay alive.

Please help. I've been searching this for weeks

It was a Isekai manhwa where female protagonist would wake up in hospital sometimes and hear her family talking bad things about her saying that she should have dies etc but everything would be hazzy and she would again wake up in this fantasy world. I read it so long ago that I don't remember what it was about, only this fragment.