My brother's ex recorded herself having sex and sent it to me unintentionally

The notification arrived in the early hours of the morning. A video... hers It didn't say anything, only the file. I opened it out of curiosity. There it was: in my bed. With my stepbrother having sex, wearing that old t-shirt he once borrowed from me. He recorded himself in selfie mode, with the camera fixed, as if he knew exactly where everything was seen from. Slow movements. Shortness of breath. She played with her hair as she slid her hands under the fabric, leaving little to the imagination. He bit his lip, closed his eyes... And at one point, he whispered my name. Not my brother's. Mine. The video lasted less than 10 minutes. But the message behind it was clear. And the worst... he said that he sent it "by mistake."