Tricks for loosening too tight hex bolts?

[DebW]

I am using a hex key - (I think - a 5-6 inch piece of metal that has about an 11/2 inch bendy part so that it looks like a tall L).

That's a really short wrench for removing a pedal. Pedal wrenches are typically 10-14 inches long. See if you can buy a longer allen wrench, or find a way to extend the length of what you have, perhaps with a piece of pipe.