Tip stalls are one of the nastier surprises in this hobby. It took me four planes to figure out that slow turns are just asking for trouble. There should be a post-graduate course to teach trainer grads about tip-stalling. Problem is, you almost have to waste a plane to demonstrate what to avoid. Anyway, keep that nose pointing downhill on low throttle, turn with rudder, keep the wings level. Better days are coming. Sorry about your loss.