Young boys need strong male influences in their lives. However, it appears that so far, your son’s role models have not been positive ones. They used alcohol and drugs and then left his life. Neither of these situations was your fault or your son’s fault. But they have left a lasting impression on your son.
Have you considered sending your son to a counselor? A school counselor would be able to see your son during the day if he is not open to going with you for counseling. A professional, neutral third party to talk to about decisions he is making would be very beneficial for your son. Counseling would provide him with additional support and guidance on how to overcome his urges to smoke marijuana. If your son is using drugs to cope with his feelings, a therapist can help him discover different, healthier ways to handle his emotions.
Your son is 18 and is close to being an adult. He should be making adult decisions. He also needs to understand that he will suffer adult consequences for his poor behavior. Often, this is something that is taught through natural consequences that he will have to discover on his own.
You can only do so much to help him, such as offering support or providing the support (counseling) that he needs. But the bottom line is that he has to choose to accept help and change. Continue to be there for your son. Encourage him to seek the help he needs, and reach out to family and friends for the emotional support you need at this difficult time.
