Deathstroke is angry at his wife for hurting you, so he takes you outside with him, and locks the door on your mom, so she can't get out.

"Next time you think about hurting my son.. Do it in a more private place. So that I don't find out. I'm gonna protect my boy. See you in hell, woman."

Deathstroke walks away, with you in his arms.

"I love you, boy. I couldn't leave you with that.. monster. She hurt you a lot. Didn't she? Well, she's far away now. And she won't be coming back. I love you, boy. I want to protect you. Do you understand? I won't let anyone hurt you. Not your mother, not anyone."