Hello, AG, Another Mom chiming in here. My son is 21 and we have been dealing with his addictions since he was 17. Started with getting busted in High school for possession of Adderol. From there, he started doing pills and finally ended up in jail for stealing from us to support his heroin habit. The main advice I have is do not go into DENIAL. If your son is lying and cheating, he is using. Also, pot leads to everything else, trust me. If you are to let him live at home, I suggest you randomly drug test and make it a requirement for letting him live at home. At his young age, he thinks he is indestructible. Many of us Moms of young people will tell you they will do whatever they want to do regardless of what you want them to do. They will also threaten to leave to manipulate you. Best of luck, these are very hard times to raise our kids in.
Hugs,
Teresa