how to say sorry for drug addiction?

You had an illness. You can't apologize for being sick. You just need to inform him about addiction. Assure him how much you love him and that addiction never affected the love you had for your son. The only thing you can be sorry for is not getting help sooner. Maybe give him some reading material on drug abuse and addiction. Take him to AA meetings and be there for him as much as you can now that you're sober. If you have done all you can and he's still angry, what else can you do? He needs to get over his anger on his own time.

I also want to add that in order for you to gain his trust back, you need to empathize for him and what he had to go through. Maybe he thinks your addiction is an excuse for treating him bad, or that you will relapse and he fears being hurt again. You need to assure him that it was in the past and that all you can do is try to move on and make a better life for the future. If he thinks you understand his feelings, maybe he will be more open to accept what you went through and realize it was not a personal attack on him. If you can't forgive him now, how can he forgive you? Hope that helps. Good luck.

Look dude (I’m guessing you’re a guy, but it doesn’t matter), you made it through your addiction and it’s now been 12 years if I’m reading right. But even if you hadn’t yet quit smoking pot, it still wouldn’t be a valid excuse for a young man to be all upright with his dad (or mom). However, you apparently did use until he was like 17, so I might could see his point, i.e. “While I was growing up you were always high!” Think first, “So? What? How’s that matter now? But say first, “I’m sorry”!

OK, you were using pot but no other drugs apparently! That’s good and you should be proud of it!!

Also, do you understand that if you were still getting high you really wouldn’t care what he said about your past use?

But your question is not about you! You possibly don’t even want to know how to make him understand what your life was like. But instead you want him to get over his anger with you!

I suggest. “Maybe he needs anger management therapy”: How about that! So now you’ve lived for 12 years without drugs, maybe he can learn to realize that; now suggesting it might be rough! So good luck! And don’t worry – you’re your own man and we’re all proud of you