You do a great job of sharing your frustration. The frustration is not only with Kelvin, but with his mother. She seems impervious to the effect a lack of discipline will have on the child's development. It's possible she is simply weary of resisting the child. But as he grows older, the issues will become more grave and it will be impossible to control him.
There are some who would suspect you were a bit rough with the child (physically) but it doesn't seem that you hurt him. You describe the scene in the room well, and you use dialog well in this piece.
Thank you for sharing this experience with us, @menace123.