Awkward attraction in New reality

For the first time in seemingly forever my wife and I actually spent time together. We had our girls and things were mostly wonderful. We went to my mother in laws house to decorate christmas cookies. My nephews love me and it fills my heart. The oldest Z we will call him clung to me and tried new foods with me and even had me running indoors. My sister in law was tolerable and my mother in law didnt murmur insults under her breath. It was a good fucking day.. and then my brother in law started like flirting with my wife and I. Now before I say much else I have to admit that he is awkwardly attractive. Like he is most definately the kind of guy I would be drawn to while single. I struggle with this sometimes because well it’s not appropriate and yet it is relentless.. he kept making off handed comments and was seemingly much more comfortable with me this holiday season. So much so that while I was laying on the floor with Z he wrapped his hands in my hair and pulled. I stifled the small moan that caught in my throat.. purely involuntary.. it turned me on. I scanned the room and no one seemed to have noticed. I told him he wasnt very nice and he just smiled and walked away. I want these thoughts out of my head. I dont wish to be attracted to him. I need to make sure I stand firm and not give into any more of this nonsense. I cant allow him to even flirt. I’m going to have to be a bit reserved again.. I could be completely misreading the situation. He could legitimately be picking on me and I’m just programmed to respond to it with sexual thoughts. In kind of a perv and have a lot of baggage when it comes to what I’ve allowed to continue in my sex life. Or he could be flirting just to flirt.. or he could really want to sleep with me.. either way.. not fucking good…