Hey @Wishful,
I think that it's really good that both you and your son are able to take a bit of a breather at the moment by being apart for a little while. As deeply and unconditionally we can love our family members, it can also be healthy to take a time out to replenish ourselves.
It makes a lot of sense that you are concerned about your son's drug taking, and as adults it can be really scary for us to see younger people engaging in such risky behavior - especially when they are our own child, or someone we love and care for very deeply. Sometimes a good strategy can be starting a more open dialogue about the risks about and and reasons why they take drugs. As difficult as it can be, it really important to try and have the discussion geared more as "information sharing" rather than instating rules (which may be dismissed outright or not listened to). At this age it can be better to suggest small "nuggets" of wisdom for them to dwell on and think about, over giving them directions.
Another really effective measure for ensuring your child's safety is to look up and recommend harm minimisation strategies for the types of drugs that they are taking. This can seem counter intuitive, and almost feel like you're encouraging them to engage in risky behaviour, but this isn't the case. Harm minimisation just allows them to be risky in the safest way possible, which is the most important thing they do if they are taking drugs. This is the best way to reduce the likelihood that something bad might happen to them. Harm minimisaiton can include things like making sure they drink water, have a safety plan for if things go wrong, and letting them know that it is ok to call you if something doesn't feel right. It feels intuitive for us that we will always love and support our children, no matter what. However, sometimes teens can be so concerned about the judgement they may face from their parents, that they are reluctant to reach out for help, even when they really want to, so it's important to let them know that it's "safe" to ask for help.
I've included this link here to harm minimisation strategies for party drugs, recommended by the Royal Australian College of General Practitioners, which should be helpful in guiding your conversation.
I hope this helps, and keep us updated!
