Your argument is basically "So what if I raped her? The other guy was going to kill her."

You've lost track of the point. At that point in history, in that location--where the context is the same--the worst evils by far were committed by a right-wing authoritarian regime, the next worst by a left-wing authoritarian regime, and the least by centrist democratic regimes (centrist compared to the other two).

If you're arguing against Hitler, "Hitler was worse than Stalin" is compelling. But if you're arguing for Stalin, it is faint praise indeed.

There has been a great deal of cruelty throughout history. Standards change over time. But within a particular time, you are somewhat safer making comparisons of which systems have led to relatively more benign behavior.

You happened to pick an example that comes out backwards from what you want. Instead of fighting it, you should just pick a different example.