BVS/Continue to refuse
From Create Your Own Story
You believe it has to be a bluff. There is no way she would actually send the pictures to anyone. You say, "That is not going to happen. Send them to whoever you wish."
Your sister is taken aback. She can't believe you are willing to risk humiliation. She says, "Fine. You win. I won't send the pictures to anyone, but I am keeping them.
Neither you, nor your sister, ever bring up the attempted blackmail again. On occasion, she sends you one of the pictures as a reminder she still has them, but nothing more. You find it is a mix of anger and gratitude that you have towards her. Anger that she tried to blackmail you into doing something like that, and gratitude for not sending the pictures.
Your relationship becomes strained over time and you drift apart from your sister. Eventually, you lose contact with her altogether. You never forgive her for what she tried to make you do.
The End