You are wise to spot the danger of drinking too. A drug is a drug and alcohol is a drug, drinking is not the solution to drug addiction just as smoking pot is not the solution to alcohol addiction...most recovering addicts and alcoholics have tried and failed at the drug replacement plan.
You are keeping it simple, you set your boundaries out and made them clear, and you are prepared to take action if the boundaries are not respected.
Whatever you choose won't be easy, but I can't imagine a life more hellish than living with addiction. I did it myself for too many years with my son and those were by far the worst years of my life.
Whatever you choose, we are walking with you.
Hugs