I need some advice on this...?

Ok, so I'm really active in the youth group at my church. Just recently m cousin Dillion promoted up 2 our youth group. Also, just recently he admitted that he was gay. Now our church believes being gay is a sin. But the youth group is treating him really bad. They actually threw his camera against a wall and broke it!! That's just wrong and it made me mad and I told them that if they're such great christians they shouldn't act like that. I'm still Dillions friend and I treat him right even we don't agree. My best friend in the entire world who I'v known since Kindergarten is one of the mean ones. She totally ditched me and now I'm standing alone doing the right thing. It's a really sucky situation and I guess I just need some encouragement. How do I handle this situation? How can I make them see that just because you don't agree with something doesn't give you the right to violate someones human rights?