If I remember my history lessons, Cornwallis's order extended to men, women and children, whether involved in the attacks or not.  All the while, of course, parading about and claiming to be representatives of "civilized Christianity."  
As for your second point, I think it was Fukuyama (?) who said that colonizers quickly forget that they are colonizers, but the colonized can never forget that they were colonized. "Getting over" 300 or so years of being colonized isn't a meaningful option.  
My family has been in Canada for about 300 years, and I am descended from slave owners.  Before you make some inane statement about my being "self-loathing" or something like that. I'm not.  I bear absolutely no personal responsibility for the atrocities committed against Aboriginals in Canada.  But only someone with no knowledge of Canadian history can deny the reality of what was done and in many ways, continues to be done.  You can't "get over" what isn't struggled with, even the unappealing.