If it broke loose it is turning on the line. Keep turning, you have to get it off anyway to put a new line on. If it twists the tube it will break off and there you go. Take it off back to the next connection. Measure the length of the line and buy that length of brake line section. Bend it using the old one as a template and install and bleed. Or cut it off just past the cylinder fitting and remove the cylinder with it on there. or leave the whole tube section on there and wind it out thru the cylinder hole.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn