Ah yes, the old corroded-in-place brake line fitting. Too late for good flare wrenches. You can try heating the fitting with a torch, then using vice grips, but don't count on this: my experience is that these corrode and adhere forever to the caliper. The old trick of using lots of PBlaster and then first tightening, not loosening, may also work.

You are probably in the market for a new brake line, since the fitting is now shot and won't come off and the only way to safely replace it is to replace the line. Some use compression fittings inserted into the line, but that is not a good idea since they can leak or come apart. Volvo sells custom cut brake lines, made of soft and easy-to-bend copper alloy, for not very much money. Get one of these and a simple tubing bender from a parts store and replace the line back to the master cylinder or junction box. Try www.Borton.com for good prices.