Want to talk to High School teacher but don't know how to reach out

Better late than never

Reach out to him ASAP. If he was that involved in your life, then you might be surprised how much he thinks about you. He'll appreciate you keeping in contact; you're not going to bother him at all. He believed in you enough to give you so much support, and he would want to see what you made of yourself despite all the stuff you've been through. Trust me on this one, life is short, and people like this don't come along too often in your life. Tell people how much they mean to you while they're still here to hear it, and not at their eulogy. Send him a message or whatever you're going to do without a second thought. You two will probably pick up right where you left off. And when you speak to him, tell him everything you said here about how much he helped you. Let him hear it.

I would say exactly what you said. You didn't reach out due to relapses and guilt etc. but now feel you are in a better place or at least will try to stay in one. No one would prefer not to reach out, but if you do relapse etc. it may be better to stay away until it's resolved-I'm not sure. As someone who had a friend with a nasty addiction, I had to eventually block them out of my life as it was too much of a risk.

Reach out asap just to thank him.
 

Have you seen Queen’s Gambit? Recall the scene where Beth visits Mr. Shaibel and thanks him for influencing her life in such a positive way?  Neither do I, that’s why she cried…