:-(. No doubt. Better safe than flooded and maybe cut up with glass tho. That's always been my worst aquarium nightmare! You could check our Craigslist since all you'd need to replace is the glass tank. I've seen many tank alone ads for $40-60.
I would just empty it. While quick setting epoxy might help, I wouldn't risk pressing on the crack, and blasting it with heat. Could cause a weak crack to fail sooner. If the tank is in your house, I would just get a $10 big rubbermaid container for now, put the fish in, and get the tank emptied.