I used when I was a kid also, lots of drinking, lots of psychedelics. Thank god I wasn't an addict.
I think my openness to drugs when I was younger probably warped my tolerance for my ex's behavior whether or not I knew he was using. It was part of my normal range of experiences once, and so I didn't question it all that much.
I quit all drugs when I had my first child. I was young and terrified of screwing up. The risk was not worth it anymore, and I don't miss it. I still drink occasionally, but never more than a couple at a time. There but for the grace of god, you know?