The problem is that FoldersInFolders is a tweak built back in day for iOS 4. It is not compatible with iOS 5 or 6. So, you need to get back to Cydia to uninstall it.
Do you have a way to put your iPad into Safe Mode? Putting the iPad into Safe Mode will enable you to load the iPad as if it's stock but still have Cydia to get to.
If you don't know if you have a way to get into Safe Mode, try this (you may have installed Mobile Substrate Safe Mode along with one of your other tweaks):
(1) Restart your device: Hold both the power and home buttons until the screen goes dark and the Apple logo then appears (the slide to unlock screen may or may not appear). Once the logo appears, release the buttons and press and HOLD the volume UP button.
Hopefully, your springboard will appear and then you can go back to Cydia to uninstall that tweak.
Good luck and let us know how you get on.
Marilyn