I'm going to expect the neighbor to pay for half the fence
Why do you think the neighbour should pay for half the fence?
He will benefit from the fence and he always pisses me off with his stupid music
I'm not sure what you think the fence and the loud music have in common. It's not fair to demand your neighbor pay for half of the fence when it was your idea.
I'll force him to pay for half of the fence.
Just as you have a right to put a fence up on your property, your neighbor has every right to do what he wants on his, that includes playing music. Forcing him to pay for something he doesn't want will end up starting a feud that no one will win.