The acceleration over time(g force) is determined by the balance between the size and shape of the wing compared to the momentum of the flies body, as long as that proportion is extremely small it would fall below the material strength of the wings connective tissue. Seeing as their wings are extremely small and their momentum is extremely small, the only real variable here is the shape of their wings(technically im referring to its aerodynamic drag versus lift both with respect to the vector of motion, but were just gonna say shape{also when i say “wing” im referring to the area exposed to oncoming atmosphere, which would include the body}). As long as the shape isnt too big in comparison to the momentum, it should be fine.

Tl;dr/eli5: if it tucks its wings it will survive. At that speed if it untucks its wings they get ripped off and the fly becomes a walk.