be at the end of your tether (British, American & Australian) also be at the end of your rope (American)1942

be at the end of your tether (British, American & Australian) also be at the end of your rope (American)
to be so tired, worried, or annoyed by something that you feel unable to deal with it any more
Usage notes: An animal which is tied up by a rope cannot reach the grass which is further away than the end of the rope and becomes hungry and unhappy.
After a day with four screaming kids I'm at the end of my tether. He's out of work, hanging around the house all day and at the end of his rope. (British, American & Australian)
See also: end, tether