The proper tool for double flaring that lasts more than a couple of flares is fairly expensive. I've destroyed a couple of the cheaper flaring tools. Supposedly the Rigid flaring tool holds up well for the low, low price of $75. I'd love to get the $250 Eastwood flaring tool, but I haven't had a project to justify that yet.The line is not a complicated shape in that area, and flaring it pretty easy and the double flaring tool is not expensive.
www.amazon.com/RIDGID-23332-Flaring-45-degree-flares/dp/B000X4K9KO
www.eastwood.com/professional-brake-tubing-flaring-tool.html