"Permanently deleted" is the same as "Purge" and both are forever in almost all cases. That is why it is a two step process with the confirmation. And how disk space is freed up after done.
Good advice often comes too late, so I'll just say this quickly for anyone else reading the post: make a copy of important datasets in a backup history. Then consider running a local Galaxy as a place to keep another backup (if you want to be able to view the data in a Galaxy UI) - or just download the files and save them. And as data ages and you need it less, move it off of the public site to free up space. You can always reload it.
Any data, on any computer or server, that you care about - make a copy and have control over that data. Put that data at least two separate places. Backups are good. The pain of doing this is worth it.
Now, I think everyone has some photos to backup, right?
Thorsten, we are very sorry this happened, and really hope things have been going smoother lately!
-Jen, Galaxy team