Only one end swivels. Try breaking loose the hard line end.

Same flare nut sizes. Alternate method: with a hack saw or whiz wheel, cut off the crimp on the rubber hose, and peel it off. Cut off the rubber hose with a knife. Both ends have this done. Replace the cut off hose and crumps with FI hose and double clamps. It will hold the pressure just fine.

Not responsible for advice not taken...