Fatal error installing new theme

Hi there,

I have installed a new theme (divi) on http://www.prettyforest.com and just activated it. I got a fatal error message on each segment of the dashboard.. I didn’t update this website for quite a while, so thought the issue might be with the wordpress version (not sure which version I was running), but it doesn’t do anything when I try to update to 3.8.1.

Wanted to delete the theme from ftp (cyberduck) but I don’t see Divi in the themes list? Anyone has an idea how to proceed?

Big thank in advance!