should we criticize ourselves for our own wrongs, and try ourselves for our own crimes?

sure.

but, not at the expense of defeating evils that were greater - that is when we need to be relativistic about it, and when we cannot be constrained, or feel bad about our own necessary atrocities.

so, we should criticize ourselves for our slavery, for the trail of tears, for the theft of indigenous land, for defoliation in vietnam, for iraq, for libya - yes. those are our crimes, and we should be held accountable for them in ways that are reasonable.

but, we should not criticize ourselves for dresden, for tokyo, for bombing isis or for anything else we had to do to wipe out forces that were much more evil than us.

we made hard choices; they were the right ones, and we should pride ourselves in having the resolve to push them forward.