It hurts when your parents prefer your other siblings it feels like they have abandon you

I understand completely. I am my parent's only biological child, and they adopted another son. He has always been and still is their "golden child". My mom had severe complications when pregnant with me and could not have any other children (she wanted a larger family), so he was the child she could never have. I don't doubt they love me, but he was always their favorite and I sort of got pushed to the side. He turned out to be an asshole and we don't have a good relationship, I'm just cordial to him because of them (my wife can't stand him). He's not a blood relative, and I don't even refer to him often as my brother. It's sad but true.