1991 GMC Sonoma rear brake line failure repair.

This line failed in the driveway. Pictures
All I did was push hard on the brake pedal.
At first I could not get the the line to seal.
I was doing a single flare.
Didn't know you have use a double flare.

It ether failed because of rust on the outside or from internal toxic old brake fluid.
It failed were it bends away from frame.
That hose on the frame is the rear axle vent tube.

It could of happen driving down the road Whoa!