Should I be mad

Okay so my friend dated my current bf before me (she was the gf before me) and she tools me she is selling her hoco dress and I asked to see it and she starts freaking out cause the pictures of the dress were all pictures of him and her amd she was scrolling thru her camera roll and I saw pictures of them that she had kept. I got irritated and layer I found out that apparently they had sex, before he told me they didn't, but that's not wjay I'm hearing and don't know wjay to do