Database corrupted getting the site crash
As webdrips has said, your error seems to be with the xmlsitemap module, and considering it is not critical for functionality, you should try disabling it.

Depending on the state of the website, if you are experiencing WSOD, you may need to disable the module through the database using phpmyadmin. 

In the system table, find the xmlsitemap module, and edit the row where the column is "status", and set that to 0.