Welcome and please know you're not alone. My son is an addict also. I have found a lot of wisdom and experience on this site, so keep reading.
As others have mentioned, it is so important to find an al anon group and attend the meetings.
Remember the three C's regarding addiction:
You did not Cause it
You can not Control it
You can not Cure it.
Addicts are experts at manipulating and lying, so trust your gut. Love your son, but don't take the blame for his actions. We're here for you.