Answer :
Answer: idk a lot about that topic so sorry if im wrong but i'll try to help
Explanation:
1.) The witnesses feel overwhelmed and joy. Now that this border is finally down and they are free and can cross. 2.) i think "a world has come undone before our eyes" means that , the citizens were so used to the border , with the wall being up and no one was allowed through. & after the fall, they finally had this sort of new freedom