Was I wrong to confront my boyfriend's ex partner? We are in an open relationship

My boyfriend and I are in an open relationship. Hes 18 and im 22 turning 23. We both see other people and are fine with it however, the person my boyfriend has been seeing as of recently is his ex girlfriend. Shes 17. They were dating each other from 2018 to early 2019. I heard them having sex yesterday and hearing him screw people usually turns me on. Then this girl comes downstairs and it turns out to be his ex. We will call her Kelly. She is aware that he is dating me. When she saw me sitting on the couch she rolled her eyes and told my boyfriend she was heading out. So I followed Kelly outside to her car and told her that I’d appreciate it if she didn’t come by anymore. She asked me what my deal was and I told her that I don’t think her presence with MY boyfriend is appropriate and that it’s disrespectful to me and our relationship. She told me if our relationship is open then i can’t pick and choose who he sees. I told her that I will talk to him about it and to please leave. After she left I told my boyfriend I don’t want him seeing his ex ever again. He told me that it’s not fair of me to dictate who he sees if our relationship is open. He reminded me that we agreed to no jealousy. I told him that there is a huge difference when it is your EX FUCKING GIRLFRIEND. He got mad and told me I was being ridiculous. This is the second night in a row that he sleeps on the couch and I’m really upset. I don’t know what to do or how I was the one in the wrong. Even open relationships have rules & limits.. I don’t think he’s understanding that open relationships ≠ doing whatever the hell you want