I don't want to help my brother pick his classes
Why not? It seems like a simple task.
I never liked him and over the years he has grown to be like his mom
I still do not think that is a reason to not help your siblings. You should at least try to help pick a few classes so you know he will enjoy them.
No, I just want to give him a hard time and let him struggle.
It is wrong to try and make other peoples lives hard. You can really make a difference and he might change when he grows up.