In love with a addict

Before you judge please don’t, because this could easily be you or may have been you.

I’ve been with this guy for 3 years, & we now have a 2 month old daughter. We have been living apart due to financial reasons. I have now learned / discovered that he is using a hard drug to get High of. I have reasons to believe this drug makes him paranoid, & delusional. He says someone is out to hurt him. He said he would stop, because he did not want to lose his family. How did you deal with a addict? I was already done with him, but he acted as if he was done with the drug.