I'm going to push a mentally disabled child in self defense
That's very intense! Why would you push your child?
Yes, he entered the room when I was drunk and tried to hug me
You should never push disabled children. You should show your affection toward those who are disabled.
I just want to make the little bastard happy and furious at the same time.
That will be confusing to your kid and you shouldn't play with his emotions specially if he is disabled as that can cause trauma and may resent you growing up. He needs much care and comfort in your care, not abuse.