I'm so sorry sweety. Guilt is a natural and healthy emotion to work through in your situation - in all of our situations, for one reason or another.
It sounds like you did all the right things to protect all of you, including your wife because you stopped enabling her disease.
It is heartwrenching to imagine and picture the suffering of someone going through the end stages of addiction. I have had to go NC with my mother, and I struggle with guilt but I try to turn it into the empathy and compassion I would feel for anyone who has the life she has. Guilt implies there is something I should/could do to help save or rescue her that I haven't already tried - and there is not. Her life is her life.
Your wife DID have the option to come home. It was through recovery.
Your loss os great and I strongly urge you to go to Al-anon AND a gried and loss support group. When I lost my dad I didnt think I needed a group, and I got by without them - now that I've tried going, I wish I had started 17 years ago! They are incredibly useful.