motherfucker! its doesnt matter what kind of relationship they have, she should know that the blond fucker fucked u up!, u knows hes a yandere fuck why the flying fuck would u not tell her shes in dabnger'¿?!
for fuck's sake, just ask her. And if she still wants to help the demon after he tried to kill you twice then you may kill her too cuz she's not a good person.