Steel has a fatigue limit - a level of cyclic stress below which it will basically last forever. Aluminum has no such limit. All aluminum things will eventually fatigue crack. That's why airframes are inspected on a regular basis, and why aircraft manufacturers have quite elaborate methods for building and repairing them so as to minimize the risk of failure within the bounds of weight and cost imposed upon them. As others have said, you can certainly repair this frame. It will eventually fail again, somewhere. If you can't live with that, you shouldn't be using an aluminum frame. Love the color scheme, BTW.