I'm mad at my aunt about (kind of?) pushing religion onto my brother.
When you say you are mad at her in the sense, what exactly do you mean? Do you mean you are angry with your aunt?
I think it was an accident but I am still angry about it.
It is wrong to be mad at a family member for their religion. You can have your turn to convince him after about religion.
I'm not angry with him but with my aunt.
Should you be angry at your aunt? It seems that you're not sure what she might've done.