So there’s this horror movie that I saw a while ago, maybe like a few years ago, and all I remember was the ending when the girl looked out the window and saw someone (or somwthing) and picks up a knife and kills her husband. I also remember that in her family all the girls killed their husbands or something like that.
Virgin Suicides?
It’s not exactly what you described (and I’m not sure if you meant it was a few years old, or if it was older and you just saw it a few years ago) but could it be “Daughters of Satan (1972)? The main female character kills her husband with a knife at the very end.
Https:// youtu.be/VZFrz6QNEsA