AITAH for feeling upset over my boyfriend having a female friend that use to like him

So we’ve been dating for 11 months (1 year this month). He met this girl in college a few years ago. She expressed she was interested in him and he said he shut her down and that he only sees her as a friend and that he does not want to ruin his friendship with her and doesn’t see her in that way at all. He didn’t tell me this till just last week to which I asked why and he said he didn’t think it was a big deal. Now we hung out as a group with a few others at a bar a few months ago and she was there. This was before I knew she liked him. Everyone else I met was nice and seemed like they wanted to talk to me but I could tell she didn’t and just avoided me and didn’t try with me at all. Now it’s all coming together and I’m thinking it’s because she liked him and possibly still does?? He said that there’s no way she still does and that it was years ago. I got upset over this and have been thinking about this all week and don’t want to keep bringing it up because I don’t want to seem insecure because his first ex made him not be friends with anyone because she was insecure and I’m not trying to be like that. But I feel like this is valid reason? Am I in the wrong for feeling this?? Would it be wrong to make him stop talking to her.