We were very lucky that my step-daughter's still-using bf dumped her as soon as she fessed up to us about her addiction. We didn't know that either of them were into hard drugs until that night. He didn't want us to contact his parents which we did anyway. We didn't know it, but he had previously been caught using heroin and his parents had him in a treatment program where he was cheating on the urine tests by timing his use. He had convinced them that SD was not using. If we called them to tell them she was, they would suspect he was still using.
The piece of garbage was also holding a bracelet that her late dad had given her as collateral for some money he had loaned her. He then shook us down for an extra $100 to get them back. It was a small price to pay have him out of our lives.
She's now in her second rehab and things seem to be going well. I hate to think how things would be if he hadn't done us the favor of splitting with her. She was still hung up on him a month later and tried to call him from the first rehab. He laughed at her and told her he was in bed with another woman. That precipitated a crisis in which she demanded to leave rehab. Fortunately, she didn't.
A few months later, he called her trying to get back together, but fortunately she was over him by now. She was dating several other boys, but not hooked on any of them. I know that relationships are not a great idea for someone in early recovery, but at least she wasn't serious about any of them and over the one that helped her get on drugs in the first place.