by the looks of the line - I doubt they are going to be reusable once you apply tools to them.

3/16 lines are cheap at autozone etc, some come preflared too in various lengths, You dont have to use the mercedes benz union splice here unless you are a purist.

If I were to repair this and it was close to an end point - I would snip this line off at a good solid point where there is no corrossion then get an appropriately sized length of new brake tubing from a parts store with correct fitting on one end (MB use metric bubble flares on ends)

cut the new line at the "other side" and double flare it with a proper nut for it - same for the line on the car and use a coupling union there (double is easier to make and its tools are easy to get). All these parts are available at any parts store for really cheap (like under 20) and a flaring tool is cheap too. Napa sell a small double flaring tool which is really easy to use under a car.

If you fancy new copper nickel lines like volvo (aka rustproof lines) and buy a roll you will need a bubble flare tool for the business end, I use an OTC brand for it, takes some practice to make good bubble flares (abt 5 or 6 times)

bending a copper nickel line is easy - the green armor line from AGS is slightly tougher to bend by hand but a small HF tool for bending the line makes quick work of it.

If you have found one point of failure in your brake lines I suspect you have other issues elsewhere too. My first bitter lesson in brake line replacement was to never swap just one line if there is rust as the probability of the whole line set being a pile of rust is close to 90%

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)