Guys I had a fight with my uncle's brother just rn

So today, we had a midnight plan to somewhere else far away from my home with two of my older and younger uncle's son. But I had to cancel the plan as my parents didn't gave permission at the very last moment. When I informed about it, one of my brother younger than me got so toxic that I kind off blocked his contact and social media rn. I am so fucking pissed rn that I won't be able to look at him the same way I used to. I told him that I will never participate in his lifetime personal or health problem ever. That guy is so young, yet he got toxic against his own older brother. I want to ask if I should talk him to again or help him when he need me the most even if I don't want to?

Trying to decypher this message rn

No idea what I just read. Isn't your uncle's brother also your uncle?

what does toxic even mean, assuming you are someone in their teens he would be around 15 and I would assume them to be a bit bitchy at that age, your response seems to be stupid and he is your family