Hi Rina. I totally understand what you are going through. I never thought that my daughter would be shooting that poison into her veins but she did. And she did it while she was living at home.
As the others have said, the important thing is that he is in treatment. Even better, he has been honest about his drug use to his therapist. That is a great start. Now, they know what they are working with and I promise he is not the first or only one there that has used heroin.
It is a spreading epidemic. As Rx pills are getting harder to get kids are turning to heroin as a cheap alternative. If he is physically addicted, there are medications that he can take. Do the research.
In the meantime, use this time to get rested and build up your strength. Get a therapist and/or continue going to meetings. No one can handle this alone. I know . . . I tried.
{{{hugs}}}
~Kathy