Bruno's recovery was rather swift. And why wouldn't it be? The bullet had barely lodged itself in his flesh. The projectile was extracted, a stitch or two was applied, followed by some bandages. Which were tenderly replaced in a timely manner by Bruno's wife.
Sure, he had damn near died, and would have done so if he wasn't an alcoholic, but the wound itself which had been inflicted on him was minor. The near death incident came from the fact that had he not been wearing a thick and heavy wool greatcoat, with a steel flask in his breast pocket. Then the bullet most definitely would have pierced his heart and killed him.
Because of how Heidi reacted in an overly protective and almost motherly way. Bruno was quite literally forced to rest in bed by the woman, and to be tended to by her as if he were a sick child. While this had some appeal in its own right. Bruno honestly believed his beloved wife was overreacting.