a load/weight off your mind idiom
卸下了思想上的重负，心上的石头落了地
an occasion when a problem that has been worrying you stops or is dealt with
I'm so relieved that I don't have to make a speech - it's such a weight off my mind! 不必作演讲让我长舒了一口气——这下我心上的石头可落地了！