Da sonst noch niemand da war ... erst mal diese Fundstücke :

https://www.dailywritingtips.com/100-mostly-s...

 100 Mostly Small But Expressive Interjections ...

 ... Phew, or pew, communicates disgust, fatigue, or relief. (Phooey, also spelled pfui, is a signal for disgust, too, and can denote dismissal as well. PU and P.U. are also variants.) ...

https://ell.stackexchange.com/questions/32976...

 ... "Phew" (mentioned in a comment above) is probably the most common interjection for such a situation. M-W says that it is "used to express relief or fatigue". Oxford Learner's Dictionaries says that it can show that someone is "happy that something bad has finished" and gives this example: ...