There may not be many options.
If LrC has not been quit since the delete, you may try the undo command but as I recall it does not work on deletes. However, your profile says you are a Beginner, so perhaps you actaully did a remove rather than a delete and it is possible that the undo will work (I don't recall if this is the case but worth a try). If you've quit LrC since the problem occured this option can't work. I don't have LrC running right now (started system backups before I head off to bed) so can't test the idea.
As you are on a Mac, it is possible that Time Machine captured a copy of your catalog shortly before the delete that you could revert to (assuming you are running Time machine). If that works, you may have to recover your image files from the Trash or some backup but that should not be too difficult as they seem to all be in the same folder.
If there is no joy from the two options above, and your "many hours" of editing spanned a shutdown of Lrc where you choose to perfomr a backup when prompted by lightroom as part of the shut down, you can restore that backup. Again, you may also need to recover deleted image files from the Trash and of cousse you'd lose any updates you did since that backup.
One last thought depends on if you had Auto Save of Metadata turned on. If so you let us know.