So my boyfriend and i have been dating for a few months now. Known each other for years. From the start, he has been open with me and told me that he is still friends with his ex. Best friends he said and they have a strong bond. He is the only guy that she has dated(she is bi). He asked me if i would feel some type of way with them hanging out. I said yes until I meet her then I would let him know if im completely comfortable with them hanging out. (I believe that if she came first i cannot have a say on their relationship) He also told me I have nothing to worry about with him however, she does have a reputation and would likely try something. At that point im like no i do not want you guys hanging out at all. Fast forward to last week, we were talking about hanging out with friends and he brings her up and im like no i do not want to hang with her yet. He tells me how they had been planning on hanging out. I went off on him bc how can u plan with her to hangout when u havent even planned our first date yet or came to meet my mom? But u can plan to hang out with her? Make it make sense. So after that argument, we stopped talking for a while. During the break time I decided its okay for them to hang out bc i trust him and thats all that matters. We tried to talk it out and told me he was gonna hang out with her anyway. You guys i have this gut feeling about her that wont go away. Should i be worried about them hanging out? Or should i trust him because he has been open since the beginning? Am i wrong in anyway? Please let me know.

UPDATE: He broke up with me.