SO and RX Drugs

We recently moved out of state which I'm thrilled about for one bc all the sellers he bought from are far removed now. But I worry he'll just find another source or make pain mgmt appts (that he doesn't need) just to access the drugs. 

He and I just learned we are expecting, and I obviously don't want my child in that environment. I'm not sure if I should leave though. Our relationship is good, communication, and I love him. We have no issues as far as arguing or anything. On a different note, He and I are also dependent on one another at the moment...he has a job, but I'm job searching; I have the car, savings, credit and so on, but he lacks all of that. 

I'm conflicted. I don't want to take his child away from him and I want to be with him and work it out and in other ways I feel a little stuck, but now that I'm expecting I'm looking at his drug past/habits in a whole new light - rethinking everything.  Baby isn't due until fall; should I use this time to see if he changes or end things now? 😞 Not sure what to do. What's fair? What's right?