Serious question about fiance

My fiance and I will be living together soon and he told me something about one of his close friends that I didn’t like.

A little about me... I was raised to not do drugs and I never will. It is part of my values and I’m against them in every single way.

Well not too long ago my fiancé told me that one of his best friends likes to do cocaine and that he has been a lil messy since he broke off his marriage. To me, I don’t care who you are... cocaine is a huge no in my book. He mentioned that he will be sure that his friend never does this is front of me and if he does to just not be so defensive about it. Don’t get me wrong, you can do whatever you want in your life and it’s none of my business to dictate what people do. I find it an issue when I’m around people who do this. My fiancé doesn’t do drugs or get drunk. Anyway, him and his boys are close and occasionally crash at one another’s place and I’m cool with it. What I’m not cool with is ever having someone sleep over our house if it’s for reasons like knocking out from getting so wasted. He lives in the same city so he has no reason to do so. I am okay with friends coming from out of town and what not and I’m not controlling. I’m just turned off at the fact that he hangs out with someone who doesn’t seem to be a good influence. This man makes very good money but gambles it to the point that he’s broke. My husband doesn’t gamble and if he does it’s just a very small amount. We both have very good jobs and are educated and want to start a family and good life. I just don’t like the fact that he has this friend in his group that makes bad choices. I am a believer in you are the people you surround yourself with and I want to be clean. Heaven forbid sometimes happens while this guy is doing drugs and we get into trouble as well. I am a very clean women and these things are not okay with me.

To make the story short, his friend is an educated guy with an amazing career yet makes bad choices.

Am I wrong for thinking this way and being against this? The guy isn’t a drug addict and occasionally does this drug but I don’t want this energy in my home or around me. I’m not trying to be that controlling partner that chooses my husbands friends. I’m just against people doing things that can ruin their lives. I think it’s the worst thing you can do to yourself and don’t want this in my life. It’s one thing if it’s a friend you see a couple times a year. But this guy is the one he hangs out all weekend.

Advice on how I should approach my fiancé?