Sorry to hear that, but if you haven’t yet, you may consider writing a shell script that will automate making of timestamped backup copies of your module. Apart from catastrophic failure protection, it creates a timeline of recent saves you can easily rollback to if you make changes you don’t like.
I found this in the Vault (warning - untested). It’s for NWN2 on Windows, but the principle should be the same for NWN1: copy module file, compress it (save space), put a timestamp in its name and store it somewhere outside game’s directory tree. You could even wrap it (if you make your own script or modify this one) around the toolset, so the module is backed up every time you close it (aka paranoia mode).
There is also NIT by @Surazal, which seems to have some backup utilities, but I cannot tell if you can do a one-click backup of a module with it.