Calm down. Nobody's calling you a liar. It can happen lke you said,
especially, as I said, with bladder tanks, since the bladder collapses
under the lower pressure and squeezes the fuel out. The dumb thing was
not getting the bladders checked before filling up and flying again.
Those bladders are held in place against the top and bottom wing skins
with snaps like you see on some jackets, and they come undone under
no-cap conditions. You're left with a partially-collapsed tank.

Dan