iCloud drive deleted thousands of my files, forever

Has anyone else had a problem with iCloud drive deleting files that were in subfolders? I migrated to iCloud a few weeks ago from other cloud services after I bought a iMac Retina and last week every single file that was in a subfolder was deleted in the middle of the night on April 15th (folders show "updated at 3:41am" etc. and they are all empty now). I've lost thousands of files, years of work. Apple made this a "high priority" case and supposedly sent it to their top engineers but they were unable to recover anything. I had assumed security protocols were in place as they are with other cloud services, like that you can go back in time to recover files that accidentally got deleted. This is not the case with iCloud. iCloud can delete your files in the middle of the night and there is NO recovering them. iCloud is NOT a safe or secure file storage system. I've lost years of work and am completely devastated.