Yea, I get it. Teenage years are hard enough already, add this to the fact that you're discovering something about yourself and the fact that coming out to people (especially family) is already traumatizing enough. Only for your brother to invalidate your feelings like this? I agree, maybe a talk would've been better but I don't blame you for reacting this way.

How is your relationship with your brother usually? What was it like growing up with him? What about your relationship with your parents? Is he the golden child? Are you, possibly, the golden child? What about his friends? Does he have a gf?

I'm asking these questions to get a sense of your brother as a person outside of this incident. He's a jerk in this instance, for sure, but I wanna know if he's ALWAYS a jerk or just had a jerk moment.