… it may be considered that an ethical admonition to “love thy neighbour” is not just in contrast with, but in contradiction to an armed neighbour actively trying to kill you: if he or she succeeds, you will not be able to love him or her. But to preemptively attack them or [even just] restrain them is not usually understood as loving. This might be termed an ethical dilemma.
I’ve been there. It isn’t pretty. And I never know what I should do to make things better.
Or just to be able to love properly.
And no, Tit for tat doesn’t work.