Was I right?

Okay. So I posted about a week ago about how my boyfriends family friend is coming into town..Now shes great but just like I was worried about, some things happen. To make things clear. His older brother's half sister is the one in town. I've caught my boyfriend check her out, clearly staring at her ass when she bends over, and then last night she came in with just a towel on to show him some Mark's super close to her ass..Was I right the whole time? I discussed it with him and how I felt, but he said I was overreacting and now he seems upset and distant...