I understand the emotional toll that those"scenes" take on your well being-- trust me.
I really wish you had family to go to-- this is a hard situation, because you are living with his mom. Have you talked to her about this? I am sure she sees his behavior.--- Is there any way possible that she would have him move out for the good of her grandchild? Maybe she would agree to go to a Nanon meeting with you-- wishful thinking on my part.
Maybe you could also talk to your boss, and explain the situation, maybe they will be extra understanding- I would hope they would. They could make it a point not to let him into the building or something.
If I were you, I would start keeping my money to myself as much as possible. That way you have something in case of emergency and to move.
Also, there are programs in a lot of areas that will help him pay for treatment--perhaps that is an option.
Hugs