Need advice

My relationship with my husband has been really rough since our son was born 3 years ago. I recently just got the truth of what has been happening. At first I thought I was going to postpartum depression /anxiety. I thought he was angry because I was having trouble getting a job. So money was tight and he was having to work all the time. But his anger was horrible like holes in the wall, name calling, and putting me down. When I left the first time he went into a psych ward for 11 days. He seemed like he was doing better for a couple months. And then it started happening all over again with the anger. I wound up leaving again, and he talked me back into coming home and that he would change. I was only gone for a week. They were changes but they did not last very long. By this time I thought maybe I was the one who needed help. I wound up seeing a psychiatrist him being put on medicine for depression and anxiety. A relationship still didn't get better, we had our good days but a lot more bad days. I finally left for good two weeks ago with my son. The fighting was affecting him and he was starting to not like his dad for yelling. Since I've been gone for 2 weeks I've been called every name in the book told I was a horrible person and well lots of other horrible things. Anyways he just confessed today that he's been doing drugs for the last 3 years. And everything makes sense now. My dilemma is that he's asking me to come back. Saying he has nobody else, that he doesn't want to tell his family. And that he has no other friends that he trusts. He's trying to detox by himself. I cannot in good conscience take our son to see his dad detox. There's no way I can take care of a three year old and someone who's trying to detox at the same time. I don't know what to do, I don't want him to hurt himself or anything else. Please help I'm really lost. Ps sorry for the long story.