Hi joanne.. i have the same problem as your son. But i hate coke. And i quit on new years ever. Then lapsed 2 month after.. then lapsed 6 week later which was this friday..
The main thing is joanne.. does your son want to quit? He needs be 100% that he wants to. This is the start he needs.
The next and this is what i do and it helps.
Delete every coke dealer, friends who have coke, family who have coke out his phone. Block.them as well.
Dont drink alcohol as this is a main trigger for picking coke up. Stay away from pubs, partys, house partys.
He will need to take hobbies up to keep him focused.
Watch louise clarke on you tube on crack-cocaine part 123 shes helped me alot watching her videos. .
Its ok to kick your son out. But do you want to see him get worse? If hes robbing off you.. fair enough.. but he needs support and guidence . But thats my own opinion. Maybe lay some ground rules. Like.. he has to stay in fri and sats for a month just so he gets off it. Just an idea. Good luck ask me anything if you need help