That’s the difference between self defense and an eye for an eye.
If they punch you and you break their arm and run away, that’s a slam dunk case of self defense.
If they punch you and you kill their mother, well…
Unfortunately considering the long history of the conflict and the obscene hostility on both fronts (they probably have good reasons to be fair), the second scenario seems more likely and that concerns me. And I don’t think the result of this helps anyone.