Should I have stuck up for my friend?

Last night I was playing Cod online with my brother and a friend. At the beginning of the match my friend walked out into the open and got sniped by my brother. My brother was like "what an idiot what a fucking moron lol". My friend got kinda quiet after that a little bit so I don't know if it hurt his feelings or not. Was this bullying?
Should I have stuck up for my friend?
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