Can’t get the quick connect off!

Hey, so I’m a single mom of 4 - pretty good at fixing things myself usually & don’t mind getting my hands dirty . But this has got me stumped . Hopefully someone can help . My ac/heater hose broke and was leaking . Okay , no problem. Buy a new hose, a new quick connect & a disconnect tool . Cool , get home - pop the hood and get the disconnect tool on and go to pull the part of the quick connect off (the nipple broke off inside the old hose) and the old quick connect won’t come off !! I don’t know if I’m not strong enough , or if the plastic melted onto the metal …. But it’s stuck good ! Any ideas of how to get it off so I can finish my repair ?