Gary,I don't really have a picture in my mind of why you are having a hard time to get the brakeline disconnected.
IS it where the line connects into the back of the wheel cylinder?
I imagine those conenctions can get pretty tight. You should use a
six point line wrench it is like a six point box wrench with a cut out in it so that you could slip it over the line and then slide down to the connection. IF you don't have one, then you may consider cutting the line close to the fitting so taht you could get a six point socket on it.
Vice grips sometimes work when everything else fails, as a last resort, you can pull the wheel cylinder and try to get it out on your workbench, as a final solution... you can buy a new wheel cylinder. I just checked... $14 They come in left or right side.
Good luck... I hope you get to bring
your truck.