I've never apologized for most of my bad behavior. I don't do it anymore, and I think that counts for something. By and large the people who got the brunt of my addiction were other addicts and I don't feel I owe them an apology. When you're doing drugs you accept crappy behavior from other addicts, that's the game and if you don't like it you stop doing drugs. I don't expect them to apologize either.
I do know that my parents wondered about my behavior when I was doing meth. But they didn't know I was on drugs. I don't see how it would be productive for me to go tell them most of the weirdness was due to that. They don't understand how you could try drugs, let alone get hooked. It would probably make them question their parenting and what's the point? They aren't having more kids. There are lots of other reasons. And sure, maybe I'm just justifying to myself why I don't apologize. But it won't change my mind.
Bottom line: I stopped with the bad behavior. I can't change it so if you can't get over it feel free to cut me out of your life.