Unpopular opinion but YTA. The gym can be a very uncomfortable place for women, it’s not uncommon to be stared at or have men take pictures of you. Even if you didn’t do it, she thought that you did and she was concerned. She was loud and recorded the event to make sure you didn’t get away with it. I’ve actually seen a few videos on social media where other women do the same thing, but from their recording you can see that men did take pictures and they deleted them after the women caused a commotion. If you didn’t want to show her your photos, you could’ve showed the employee and given them a warning about your own spicy pics. And maybe I’m being too wary but it seems unlikely to me that your/your gf’s nudes are the last pictures on your camera roll. General tip, but those somewhere more secure. Last thing, your comment about her leggings being see through was unnecessary. Maybe just don’t stare at her ass? And if you do, maybe keep it to yourself and don’t make it an irrelevant opening comment?