I think you are in a domestic violence situation and it just so happens that the abuser smokes pot. Domestic abuse takes many forms, blaming you for everything, outburts of rage and violence, verbal, phsycial, and sexual abuse.
Your DD hiding under the computer desk should be your last straw.
You are doing everything on your own anyway. Why do you need to stick in with something that he's not even willing to put time/effort into?
You will feel better when he goes back to live with his mother. She can enable him all day and night. And if I were you, there would be no visitation unless he's passing a UA.
But I'm a bitch.