Are you kidding me? Just because someone is on top hitting you does not give you the right to shoot that oerson. Calling henche.
Well, it comes back to what we were saying before. To use deadly force, you need to reasonably believe (so objective and subjective) that you are in imminent threat of death or grievous bodily injury, and that deadly force is necessary to stop it.
Someone on top hitting you would not necessarily satisfy that, but depending on the circumstances, it could.