The bottom drops/falls out of one's world phrase
One loses all purpose, hope and confidence of life.
When she was diagnosed with breast cancer, the bottom fell out of her world.
When he was sentenced to death, the bottom dropped out of his parents' world.
To fall into a hopeless or depressed state
1. Having got an unlucky outcome
2. In a hopeless situation
To publicly show one's feeling of sadness, guilt, or anger about something or that one is pretending to do so.
Normally, this verb in this phrase is conjugated in past simple tense.
The origin of this phrase is not clear.
Said when one is looking back on something enjoyable or worthwhile in the moment that it was happening even though it was impermanent
The party came to an end, but it was fun while it lasted.