When I discovered that my son and his girlfriend had relapsed on meth, using needles, and that people were coming and going from their home, I called Children's Aid where I lived and they connected with Children's Aid where my son lived, who investigated and removed their 2 year old child to a "safe house" where even I didn't know where she was...but I knew she was safe.
The girlfriend/mother of the child had 7 years recovery before she relapsed, and immediately got back on the recovery wagon, and got her child back after 6 months of sobriety and positive "actions' like meetings and working her program. Sadly, my son didn't follow and his girlfriend banished him from her home and her life (wise girl).
I strongly believe that someone must be the voice of the child. They are the innocents here and someone has to protect them. If I am that person, I will do so no matter how much it costs me in my relationships with anyone else.
Please do what you need to do. This child's life may depend on it.
Hugs