Might I ask why you need one? [If you don't want to answer just poke around the spells section, you'll find something] I doubt what the person did was so horrible you need to cast over them, but maybe it is. I recommend doing some soul searching to make sure this is really the path you want to go down. Also, should you choose to cast over them, please use some restraint and pick a spell that fits the crime. A death spell because they stole your boyfriend/girlfriend is a bit much. But if I were you, as hurt as you are, try to let it go. Holding on will cause you more pain.
Lol sorry if I upset you, most people who ask for revenge spells are clouded by emotions. [I've been there] I didn't think you would use a death spell, I was using an extreme example but I have been asked by users for death spells, spells to have the person loose everything, even a miscarriage spell, all because they 'stole my boyfriend' [or they cast a spell to win him over so an eye for an eye] in the moment most people will cast any curse to make the person suffer. It's wiser to wait a few days, clear your head, and ask yourself if it's really worth it.