I had a bit of a meltdown today because of anime
Why did anime cause you to melt down?
My brother is a big anime fanboy and he is forcing me to watch a lot of anime with him.
It is not good to be forced to watch something that you don't want to watch, so it is understandable why you would have a meltdown. It would be better to avoid them in the future so avoid anime for now.
I can't stand back and watch anime control my brother anymore.
I don't think you can keep your brother away from anime. But if you don't like it, don't let him force you to watch either. You should both be allowed to enjoy whatever activities you prefer in your free time.