I openly hate my brother-in-law
Why do you have to openly hate him?
I hate the way he treats my little brother
That's horrible how he's not treating your little brother correctly. He deserves to be talked against, and your sister needs to hear about it as well. No child deserves to be harmed by their father.
I hate to break it to ya but I was joking and he is a pretty good dad and isn't harming my brother. I just decided not to like him because he's gay. Dark times are ahead for him.
It doesn't matter what his sexual orientation is, that is not something you should hate him over. How would he feel if he were disliked because of things he can't change? Why not get to know him a little more, perhaps he can change your mind!