I'm at the end of my rope.

我受够了（我已忍无可忍）。

at the end of one's rope:忍无可忍    例：If you continue to treat me like this, I'll leave you. I'm at the end of my rope.再对我这样，我就离开你，我已忍无可忍。After six months on strike, the workers were at the end of their rope.工人们经过6个月的罢工后已经精疲力竭了.