Narcissist ex using my Netflix and gave it to the girl he is seeing? What should I do other than change the password?

Just change it and say nothing. He wants a response.

Just change the account and don't even tell him about it. Don't play the "I caught you..." game, since he will relish in the attention and drama.

He is looking for a reaction. Just change the password and block his phone number. Time to move on to better skies.

Why haven't you changed your password? You realize that he can change the password himself, right? If he has your password, he has admin privileges. He can change the password, change the contact info, keep the billing info going (so you're paying), and freeze you out.

Cut ties. Narcissists are impossible to deal with.

Yeah like some have suggested change the password and don't feed his ego. Starve him of that attention he wants.

deactivate ur account

Just cut him off and leave him in the past.

Kick him in the balls.