I, 30f, have been with my bf (now ex-boyfriend) 36m, for eight years. He knows everything about me and he knows my family, but I never expected him to behave the way that he did. Let me start at the beginning:

Yesterday was my birthday and we had made plans to spend the day together. We were going to go shopping and out to eat because I wanted to keep things small and simple this year. He lives about an hour and a half away from me and told me to call him when I woke up, so he could come down early. I woke up at 9am and immediately texted him, before getting ready for the day and going to run some errands. I kid you not, this man had me waiting ALL DAY for him. I texted him again at 12pm, asking when he was coming, and he said that he had to "finish his laundry." I didn't mind that, so I said okay.

He called me around 1pm and we usually sit on the phone for hours, talking or doing other things, and we did that until about 4pm. By that time, I was getting upset because we had plans and I had been waiting on him all day. Fast forward to about 8pm, and he FINALLY shows up. It's clear he's upset, but so was I. I hadn't eaten all day and I was hungry.

Now, I invited my siblings to come, and this is where the problem happened. My younger brother, 21m, is openly gay and has his own sense of fashion. If I can remember clearly, he was wearing shorts, a crop top, and a top over his shirt so that you really couldn't tell that he was wearing a crop top. And I should also mention that the shorts weren't super short either. He dresses like that daily and I didn't see a problem with it. If I'm being honest, he had on more clothes than I did.

My boyfriend saw him and didn't say anything. We all got into the car and headed to the restaurant, but halfway there...he turned the car around and said he wasn't going into a restaurant with my brother dressed the way that he was. He then told him that he had to change his clothes, and that made my brother uncomfortable and upset. He told my boyfriend to pull over so he could get out of the car, and I said no. It was in the middle of the night, on a dark back road, and I wasn't letting him get out of the car.

I didn't understand what the issue was all of a sudden, especially when he clearly saw my brother's outfit before we left the house, but I was pissed off and I knew right then and there...I was done with this relationship. When we got back to my house, I told him we were done, and he said he was fine with that before leaving. I thought I'd be sad about us breaking up, but I'm not. It was a long time coming, but now everyone is saying that I was too hasty in my decision to break up with him. So, AITAH?

Edit: I need to also clarify that my ex knew my brother was gay the whole time we were together, and never had a problem with it. My wording was off, but what I meant was that his hidden homophobia had come to the surface. Not once had he ever expressed his dislike for my brother or became hostile towards him like he did last night.