Let me be gentle here,
You in world of hurt there Sam....
You say it is the potable pump suction fitting, that makes it at the bottom of the tank. That is tough. There are some adhesive system that claim to work on PE, but none that I am aware of are approved for drinking water.
Best answer (and one I have used), find a fabricator that works in Polyethylene. He will have the stuff to weld on a new fitting.
The next try will work only if you have a larger hole elsewhere in the tank. Get a "Bulkhead" fitting. (if you try McMaster-Carr, be ready to look at a lot to get the right part.) You put it in by redrilling the hole for the new fitting and putting a wire from resized the old hole though that larger hole and sliding the fitting down that wire.
I wish you luck.
A lifelong waterman and his bride going dry places for as long as the fuel money lasts.