If she’s grieving the breakup, that’s natural and she’ll get over it. You can help her with the pain and remove any lingering infatuation with this spell:
And this is how to do a binding using poppets:
Then you can use that same bound poppet for the relationship removal spell that you made for the binding and turn it into basically a death curse. It all depends on what intention and visualisation for the future that you hold when you do it. Think about the energy being in that state NOW, what that looks like and how it feels, the satisfaction and relief and gratitude for it working, (leave ALL negativity, doubt and fear at the door and do not bring any of that into the ritual) and know it is on it’s way and already manifesting.