If my heart was heavy after the police-involved shootings of African American men in Louisiana and Minnesota, waking up to the news of the slaughter of police officers in Dallas has broken it.

What was a peaceful protest in Texas’s third-largest city was marred by an ambush that reportedly included a madman with a racist vendetta. “He said he was upset about the recent police shootings,” Dallas Police Chief David Brown said. “The suspect said he was upset at white people. The suspect stated he wanted to kill white people, especially white officers.”

In the end, five police officers were killed and seven others injured. And this nation has forever been scarred at a critical time.

The killing of Alton Sterling in Baton Rouge on Tuesday and Philando Castile in Falcon Heights, Minn., on Wednesday understandably renewed national outrage over excessive force by police against black men. The videos of their shootings and their aftermath, particularly the one shot in real time by Castile’s girlfriend, were unnerving, horrifying. They shocked the conscience as much as they crushed the soul. These videos bared for all to see the generations-long terror experienced by African Americans.

Then Dallas happened. The worst attack on police officers since the terrorist attacks of Sept. 11, 2001. That it happened against a progressive police department with good community relations makes the loss of blue lives all the more devastating.

But here’s what troubles me about what will follow.

A necessary and clear-eyed national conversation about how black lives matter as much as everyone else’s could be damaged.

Movement toward long-needed and common-sense reforms that foster better relations between the police and the communities they serve could be halted.

More important, I fear the excuse this gives other racists to act on their hatred.

We know the name of the man who was believed to be part of this. I won’t say his name. But I will say this.

God damn him for what he did to the Dallas Police Department.

God damn him for what he did to the people of Dallas.

God damn him for what he has done to the Black Lives Matter movement.

And God damn him for tearing at the fabric of this nation and using “America’s original sin” as his excuse.

Follow Jonathan on Twitter: @Capehartj