What do you feel is wrong with him saying "he responded with "I hate when you bring that stuff up, it makes me feel like crap" "? Shame is a huge part of the life of an addict.
You ask such a good question - how to get yourself emotionally well. It's work. For me, it's been about reading many great books, going into therapy, looking at my own past and issues. Working on letting go of his problems, they're not my job to fix. Therapy helped me a lot, but you have to find a remarkable therapist. If you can't afford it - go to Alanon. It's free. And the focus is you. How to get you well. How to live a full life.
I think you're really asking the "right" question! Good for you!
I think possibly we are not understanding what the word "detachment" means - ? I don't think it means taking over and doing everything. Actually, I think it's pretty much means the opposite of that. Let the balls fall at his feet and let him pick up the balls (sorry for the pun) that are his. You take care of yours. Does that makes sense?
Many times we do need to physically leave. Whether for a short time or forever but . . . learning to detach is such a valuable way to live on every single area of life, might as well use this opportunity to learn it, right?
Have you read Melanie Beattie's book "Codependent No More"? That book as an incredible start on this road. A life changer, IMO!!