What happens to old bitcoin addresses? I've read that they never get destroyed, but do they get reassigned?

The story is I sent some bitcoin to an exchange using an address I've used with them before, but then found out that they had just retired/stopped using that address. I saw the transaction coming through though. Where did the bitcoin go?? Is there an official network that manages bitcoin addresses? Please help, it is a rather large sum.

Address in question: 12aAEnfc6192cm4KLfV5eY13jYRqy684Ym transaction ID: 0db1e2f9f4233592b5f6ac5c881727e3c5694cfbd21af1744bfb11d069a1ae2d