Should I continue to help and stay in a relationship with my bf who is an addict?

We have been together a year now. In April he hit bottom. He was going through severe withdrawl from opiates and asked me to help him along with his family. We found a doctor who specializes in the suboxone detox. My bf started the suboxone but started using again. This has happened at least on 10 occasions where he has me take him to the doc. and doesn't follow through. Also the dr is prescribing xanax which he is abusing as well via his script and what he gets from his friends. He currently is living with a dealer as well. I'm at my wits end, I love him but I don't know what else to do anymore. When he is semi sober which is rare he is a sweet guy. These drugs make him cold though and cause a serious rift between us do to his behavior while on them. We were supposed to move in together but I am scared because I have children and don't want them to see this. I feel bad because I don't know if leaving him is abandoning him (although it feels he has me). What do I say to him if I do?