In her lawsuit, she claimed the city was partially responsible for her injuries.
She said that the day before the attack, a police officer had assured her that her abusive ex was about to be locked up.
A jury agreed and awarded her $10 million.
The state's Appellate Division threw out the judgment on Friday, holding that the city wasn't liable.
Valdez's attorney didn't immediately return a phone call.
The man who shot Valdez killed himself after the attack.