Your instincts are really good...trust yourself.
You only knew him for seven months during which he was using for at least part, if not most, of that time. You don't really know who he is...he probably doesn't either. In active addiction, the people in their lives are to be manipulated to make taking drug easier or they are discarded. Nothing outweighs the need to use.
He wouldn't be the first addict to go from relationship to relationship, so he may well have found a new one in rehab.
It doesn't really matter, at this point, whether he's ended it. What matters is that you believe down to your toes that you are worthy of being loved and valued and recognize that he can't give you that.
Someone here says, "Pray for him and stay away from him," and that's really good advice.
Sending you a hug.