Welcome to Medhelp and the Living with an Addict Community. Congratulations on getting your son into rehab prior to his 18th birthday, he now has a foundation that he can draw upon. Many times an addict will say that rehab ruined their using. While not completely, as people do relapse, it helps to have had the basics of recovery given to them. That being said, you cannot force an adult into rehab. Of course, if you have the insurance available, you can be ready with information as to a |Relapse Prevention Program in a rehab at the ready. Mostly, what we can do for an addict who relapses, is to let them know that we will not make it easy for them to use. That we will only support them in sobriety, but will not support them (with a soft place to land - shelter, food , money, ) in their relapse. You can find out if he is using definitively by insisting that they do a drug test, which you can buy and administer at home. There is a group that is important for you to know about and become involved with, and that is Alanon or NarcAnon. It is there that you will talk with other family members of Addicts, and learn how to stick to your guns, and not enable the addict. It is there you will find support to continue to hold your ground, and not allow another person's addiction destroy your own life. Because addiction is a family disease, you must learn how not to be as sick as the addict., because addiction will do that to you. Mostly you need to understand that addicts relapse, it is a long process to get into long term sobriety, often. You must steel yourself to the facts and stay tough for your own sanity. We are not able to help our children if we fall apart. We have to set the example and stay true to it.
Your son needs to be re told by his doctors and by yourself, that his heart condition is being exacerbated by smoking marijuana, if that is the case. The reason i say this is because, as you well know, marijuana is used regularly for medicinal purposes, so it might be that your son is well aware of the fact, and is thus resistant to believing that he is harming and not helping his condition. Any confusion needs to be addressed, by doctors.
I'm really sorry to hear how distraught you are by the knowledge that your son may pick up due to his coming of age. You can no longer treat your son as a dependent. He must learn to live and stand on his own, and take responsibility for his choices, like any other young adult. You have to let go and let him live his life, and be responsible for his choices, while always letting him know that you care.
We're here for you, in the days, weeks and months ahead. Please continue to let us know how things are going. We're here for the long run.
PS I think it's important for you to continue talking to your son's Addiction's Therapist, from the rehab, or another Addictions Therapist, you can find in an outpatient clinic. It is there that you will find your best advice, moving forward. God bless you for being a good and caring mother.