I agree that our history is upsetting, but the rampant death and inhumanity of European wars was far most costly in terms of human life. And yet no one is constantly talking about the end of Europe like they are the end of America.
Unless you count the far right in France and Germany. There is another side here, and one that has been valiantly fighting the oppressors in America for its whole history. They are called Americans--black Americans, white abolitionist Americans, Quaker Americans, liberally minded Americans. And this "side" is winning, despite the carnage you see.
One hopeful example: I called my older brother who taught for 12 years in the almost all black school a couple blocks away from Tops where the massacre was. I asked him if he felt all that work he had done educating the black American poor inner city school children had been destroyed by that one white supremacist with the military weapons. Children in the 6th and 7th grades (about 10-13 in the US) came to school for two meals a day as many had one mother working two jobs, and some even had no mother at home. He was the only person who gave them hugs and spoke well to them. He said, No, he doesn't feel that way. White teachers and others still show up every day and are welcomed and respected, maybe now even more so. It gives me hope that the violent racist side is losing. Kindness doesn't make the news.