Réponse:
Hey there,
I hope you're doing well! About your letter, I don't think that your parents love your brother more than you, they most probably love the both of you equally. They each share unconditional love for the both of you, and they were probably huddling over your brother because they want to make sure that your brother is okay.
I also think that the reason they told you that it's your duty to take care of him because one, they trust that you'll take good care of him, and two, they love you so much that they are training for the future so that taking care of others wouldn't be a problem for you later.
I hope I helped you to ease your mind, and rest assured, they love you both equally!
Write back! Best wishes,
(your name)
