This is a problem of legality.

Where, you are considered the aggressor even when she started it.
You are considered the more deadly, even if she has a knife or a gun.

Every cop knows that it is easier, in court, to beat a murder charge then it is to win a fair divorce or battery charge.

In cases where she is blocking your way out of a house, the recommended course is to jump out of a window.

Because, if you touch her you are already considered to be "touching" her with intent to kill. So, there is no legal reason to hold back. You are already at maximum level.