AITA?

My fiancé have been together for 2 years. Before we got together he liked this girl that hung around with my brother in law’s girlfriend, we’ll call her Lucy. My fiancé and I were friends at this point through my brother, and when I asked my brother if he still had feelings for her my brother told me no, she’d rejected him. We got closer and the rest is history. Lucy, my fiancé, his brother, his brother’s girlfriend, my brother and my brother’s girlfriend all work together, for reference, so we all know Lucy personally. I was never super close to her but we spoke civilly at work whenever we were on shift together. I noticed after my fiancé and I got together she started either flat out ignoring me when I tried to speak to her or would give me one-word answers. She also started getting snappy with me. I didn’t think much of it originally, but it got worse when I got pregnant. She’s very weird with my fiancé’s brother’s girlfriend, borderline obsessed with her since she’s her only friend, so I originally presumed she was jealous because I was spending so much time with her due to seeing my fiancé’s brother a lot. I mentioned to my fiancé a few times that maybe she was jealous of me and him, which didn’t make sense to me since SHE rejected HIM, so I didn’t really believe it. It just confused me because she never seemed bitchy to anyone else, just me. Well, a few days ago we were talking about some drama kicking off at work between her and another girl. I mentioned again how she’d treated me before my maternity leave and suggested the possibility of either her being jealous of my friendship with my brother in law’s girlfriend or her inexplicably being jealous of mine and my fiancé’s relationship. He then decided to tell me that she actually DID like him when we first got together, which is why she spent 1.5 years talking to me like shit under her shoe. When I asked why he didn’t tell me, he said he forgot about it because it didn’t seem important, basically brushing it off. I got annoyed and told him I deserved to know why someone was talking to me like shit. My brother in law’s girlfriend told him months ago. I ended up dropping it. Today I spoke to my brother’s girlfriend about it. She already knew and better yet, my fiancé told her not to tell me. So not only did he deliberately keep it a secret from me, but he also lied about not telling me just because he forgot and it didn’t seem that important. He claims he didn’t want to start an argument, but when I asked why he thought I would start an argument over another girl liking him 2 years ago when he’s not cheated and I’m not threatened by her, he didn’t really answer. Just kept saying he didn’t want us to argue. So, AITA for being annoyed at him and feeling like he’s broken my trust?