Supervised visitation?

Can anybody give me a little advice. Long story short. My ex (father of my baby) was and is a drug addict. His family are very dangerous people. They all smoke and do drugs infront of their kids. I'm not willing to let my baby near drugs. I'm not against drugs at all but I just haven't been brought up around and involved in drugs. I've been advised to do everything I can to safeguard my child. I've told my ex if he is clear from drugs then he can have visitation. What happens when the visitation is supervised? Would it just be me, the baby, him and a professional supervising the visit? Or would his family be aloud in there too? I'm terrified of his family and all him and his family have done so far is cause me abuse, depression and anxiety. Please can someone give me advice on this? Thanks.