My son was involved in an accident, his fault, I am the policy holder, will I be used for damages?

You are not likely to be sued, unless you were directing his actions at the time of the accident.  Assuming your son was a permissive user of your vehicle at the time of the accident, then your insurance company should cover any damages suffered by the accident victim(s), as well as provide a defense for your son in the event he does get sued.  You should notify your insurance company immediately so that they can open a claim and begin their investigation of the accident.  Failure to notify your insurance carrier could result in a denial of coverage.