Only if you have a backup to restore from, like Time Machine or a clone. If you could get ahold of an 11.1.1 installer you could do it if you also trashed your .plist and associated files. You might be able to do it by trashing the 11.1.2 and replacing it with a copy of 11.1.1 in Applications, again trashing the .plist et al.
Sounds like a mess. I'm having trouble too (can't add mp3's to the library). Think I'll wait for it to get sorted out.