(I looked at your profile from your chat request.) Cassandra, you need help. You can't self medicate away the trauma of rape.
I don't know if your son's test will be positive for meth. I do know he is in danger from being in the care of someone high on meth.
You need to get clean. Please type "addiction help" and the name of your city in Google search. Call your local recovery/rehab center. Be the mother he needs.
I'm sorry you're scared. I hope you find your way. You didn't deserve what's happened to you. You deserve a happy clean life.