keep crashing firefox everytime I click on it

You will need to do following:
Option #2 or #3
https://everhelper.me/help1.php

Unfortunately, you can't keep older version for a long because new FF57+ will automatically disable it. There is nothing we can do, that's how Firefox team implemented. 
We try to fix everything that is possible.

Highly recommend using EverSync to backup your dails.
https://addons.mozilla.org/en-US/firefox/addon/fvd-synchronizer