Fuel fittings

I was trying to change my fuel pump recently and I think I've tried for let's see.....2 or 3 hours at least to disconnect the damn fuel return line.

Everything is disconnected BUT that damn line...

I got a fuel fitting disconnection tool but that thing doesnt seam to do the trick (got the metal one)

The line doesnt seam to be "stuck" or glued to the other one because I can twist them (one clockwise and the other counter-clockwise).

Someone tell me if I'm wrong, but from what I understood, you gotta stick the disconnecter in the female end, press down and then pull the two lines appart. I've tried that for HOURS in all the freaking ways possible and no result. I seriously felt like just ripping off the gas line but....yeah bad idea...lol

So if any of you have some sort of trick or solution to my problem...any help is welcome (also I used plenty of oil penetrant). I guess my last resort would be to cut the line and use a flare tool to fit a new one...but I'm kinda worried that it's going to be tricky in such a small restricted area...

(btw car is a 99 cavalier 2.2 OHV)

Thanks!

Place the tool going into the female bulged side. Push that line into the fuel disconnect tool, while pulling on the male fuel line. There is 3-4 prongs inside the female side which have to go over the retaining lip on the male side.