How Can I Find a Rehab Center in Sacramento, CA?

My ex-boyfriend and I broke like two years ago and I have never seen him since the night I told him that we are over. Last week, I received a call from our common friend that my ex-boyfriend has been taking drugs. I don’t know if I have anything to do with that but I want to help him. He is still my friend and I can’t just ignore and him and our past. Please help me find a rehab center in Sacramento, CA.