Another school shooting. My knees go weak as I sit on the couch searching for details. Although I have never been involved in one of these tragedies, they are deeply personal for me.

It is every parent’s nightmare to get the call that his or her child has been the victim of a shooting. The call I fear is that my child is the shooter. My handsome, blue-eyed son—we’ll call him Russell—is autistic and mentally ill. Now 18, he is at that vulnerable stage when young men so often go off the rails. He is also old enough to buy a gun.

Both sides of the gun-control argument agree that certain people should not have access to guns. Throughout Russell’s difficult childhood, I have known that he is one of those people. I never considered that the law would allow him to purchase a gun, and that I wouldn’t be able to prevent it.

Russell’s struggle started at 3 years old, with hallucinations both visual and auditory. He’d see dead people lining the streets in old-fashioned clothing, or owls in his closet, or dinosaurs in the hall, or dragons—lots of dragons, which would swoop around him and protect him with their wings. He’d conjure them for comfort to hide him from a world he did not understand.

But the comfort came at a price. The wall of wings would clap around him, trapping him in a terrifying void, a void where he could not see or hear the real world, or any of us who lived in it. He’d curl up in a ball in the corner of the classroom, or in the middle of the playground, and soil himself. I’d race to the nurse’s office with fresh clothes and fold him in my arms, hoping that love would seep through where words could not.

In young children, the bipolar swings that adults experience over the course of days is sped up like a roller coaster. Russell’s hyperactive peaks plummeted into depression or anger 15 to 20 times a day. The shifts were sudden, requiring only the slightest pressure on his hair trigger. One minute, he was bouncing off the walls so joyfully the house would shake. But give him a blue dinner plate instead of his favorite green one, and he would angrily sweep his arm across the table, smashing the food to the floor. I tried to assert authority, but as a single mother, it was hard to embody both the softness needed to get him through the day and the firmness required of discipline. He knew I had limits, and he didn’t hesitate to exploit them.