Drained,
I am glad you are filing for the perm RO. And you are filing for the divorce. At least you are taking steps to protect you and your child now. Remember it can be dropped later if he wants to get clean, and does it.
He is an addict and until he sees that and hits bottom there is nothing you or anyone else can do for him.
I went through a divorce and it was hard so my heart goes out to you at this time. My ex was not an addict but very controlling and abusive to me. I was afraid of being alone and not knowing what was going to happen, but I am better now mentally than I was while married.
Turn to your HP for help he/she will guide you in doing the right thing.
Hugs and prayers coming your way