Apathy always works with me.
What is apathy? Apathy is the absence of hate, AND the absence of love.
It's nothing. Apathy is nothing.
So, if you want to stop these negative interactions, that is what you do. You don't react to the things that he does, the things that he says, or anything. Don't react at all. No reaction!!
Don't hate what he does, and don't like what he does.
And if there is any interaction, joke it off and keep going about your life.
And why is he living at home at age 23 anyway? That's what I wanna know !!!