Son

My 19 year old who cannot seem to leave marijuana alone. His dad and I have begged him, pleaded with him, prayed about it and cried our eyes out and he will not do it. He was a straight A student and when he turned 17 1/2 a family member introduced him to it and he chose to do it and has ever since. We have told him not to smoke in the house and he has refused to abide by our rules and denies that he did even though he leaves his bedroom window open and you can so smell it. Then when confronted he gets mad at us for asking him about it and thinking we could ever think such a thing. We are to the point of making him move out, but you know with that comes all the guilt, are we turning our back on him and all the what ifs!. We are just heart broken and lost at what to really do.  I have so prayed for this child and I know I have to give him to God and whatever God's plan is it will happen, but it is sure hard to let go. Thank you.