Fixing a leak in my compression fitting

You have Qest brand pipes and fittings and that's not a compression fitting, it's just a crimp. If you have enough length, just cut it off cleanly at the back of the crimp and purchase a Qest compression fitting to replace it.
Those crimps are notorious for failing because they're made out of aluminum and they stretch over time. If you can find replacement copper crimps they will last forever but compression fittings will also last a lifetime.