The upside is the possibilities contained in knowing that everything is up to us; where before we were experts in the array of limitations, now we become authorities of what is possible.

还是句意懂，结构懵。。。

请问老师，如何理解where状语从句结构？

我一般常见where+一个陈述句，或者肯定句，比如，i like the park near where i live.
(自己造的不知道对不对，不对还请老师指出)

但基本没见过where + 一个before 再跟一个句子的，before也可以作为一个引导词，后面不就没主句了吗？那不就成了一个关系副词引导一个状语了吗？

如：this is the place where before i came, he had been here. 

(自己造的不知道对不对，不对还请老师指出)

 before i came 是状语。把后面主句he had been here 删了，句子不就有问题了吗？