Has a lot to do with everyone who's friends with friend 2. Friend 2 did something that proves his untrustworthiness, and lack of loyalty to one of his best mates. If he is willing to do something like that, one of the number 1 things that you specifically DON'T do when you are friends with someone, what else is he capable of doing? He didn't stop until he was confronted with evidence. He has broken the trust of everyone who is friends with him through doing this to one of his best mates.

I don't think it's unreasonable to rally support to oust someone like this from a group. He did this once, he'll most definitely do it again if literally nothing comes of this.