Or, alternatively, what did you do to another person which got you blacklisted from their life?
I second this. It’s your life and you don’t have to, but it would not be too late to reach out. If you want you can explain that you had to cut ties to get clean. Chances are they had to do something similar and will understand. And you don’t have to jump back into a friendship. Just wishing them well might still be good for both of you.