Is AUTHOR wrong in the post ? POST : Throwaway because all of my friends know my real account. Sorry for the formatting, I'm on mobile. If you see any mistakes feel free to correct me, English isn't my first language.

So some background, my little brother and me are actually half brothers, but neither of our fathers were ever in the picture. My mom was super young when she had us and she never actually wanted kids, so she dumped us with our grandfather and only occasionally visited.

 Now, my grandpa is an amazing man but he worked full time and never really had much time for us, so me and my brother were always super close. We always felt like it was us two against the world. 

My bro is best friends with this kid, B, they've know each other for a couple of years and instantly connected. 

Now, B has a huge family, and I've never been able to keep track of all of them, I'd seen him around before but 5 months ago was the first time I actually had a conversation with B's eldest brother. We hit I off right away, he's funny, charming and we share a lot of hobbies. We started hanging out, and I'm not sure when hanging out turned into dating but we just kinda fell into it. 

A week ago he asked me to be his bf officially, I was over the moon. However, B found out yesterday when I came to their house and he went ballistic. He told I had turned his brother into a faggot and stuff like that (the bf is bi, but hadn't come out to his family).

My bf and I basically ran out of the house to escape him, but after twenty minutes into lunch I told him I was too uncomfortable, that he had to go back and figure things out with B. He agreed, we paid the check and we went our separate ways.

When I got home my bro was furious, he told me B had texted him about the situation and accused me of ruining their friendship. He told me I had to break up with B's or he'd never speak to me again. He then went into his room, slammed the door and won't speak to me no matter how much I plead, it's been about two hours.

I'm thinking about breaking up with my bf because I feel like if I don't I'll lose my little brother forever, but it also feels like a betrayal to him.

So Reddit, WIBTA?