Extortion and blackmailing are interlinked crimes. If your girlfriend is threatening you to make a morphed video or any sensitive personal video public, then inform the police in the first instance. You can also report if she blackmails you on the internet to spread videos. Blackmailing can possibly fall under the categories of Criminal Intimidation or Extortion, both being punishable offenses under the Indian Penal Code 1860. Blackmailing can be Criminal Intimidation under Section 503 of the Indian Penal Code. But you need to keep your evidence prepared before filing an FIR.