If you say that you are at the end of your tether, you mean that you are so worried, tired, and unhappy because of your problems that you feel you cannot cope.

A tether is a rope or chain which is used to tie an animal to a post or fence so that it can only move around within a small area.

If you tether an animal or object to something, you attach it there with a rope or chain so that it cannot move very far.