When one of these racist assholes decides to attack you, you have a fraction of a second to recognize the attack and begin responding.
I would be completely on board with a lethal response. This will not end until the racist attackers start getting a bad case of lead poisoning.
You could tell the white gal holding the toddler knew it was coming when she leaned her body away from the attacker. Swallow your pride, get up off of “their” bench and politely leave.
If they follow and still seem to pose a threat, pull your gun. These punks would back down.