How do you say ex-girlfriend in spanish?
Or, more simply put, just say, "mi ex". That is commonly said and understood but most spanish-speakers around the world.
I tend to rely on an old favorite:
Ella en cuyo corazón se puede enfriar una botella de champán...
But that's just me!
in Chile you can say: "ex Polola"... but by saying "mi ex" you will be understood as well.