28 years old is way too old to be living with parents. Just remember that love bangs the door shut as well as opens.
I'm sure you realize that when your son embraces recovery, he's going to have to dig in for the long haul, he's going to have to really focus on how to learn to live without his DOC.
But the parallel is here for you, too. In your recovery from your son's problems, you have to dig in for the long haul. You have to really focus on how to learn to survive and thrive even though your son is floundering. You have to learn how to not hang your happiness on the most dysfunctional people around you. So keep coming back here because we are a group of people who are learning, and have learned, how to do that ourselves.