Jarp my heart goes out to you and how difficult this has been.
I do want to point something out. A mental health worker or even a doctor making broad statements such as "brain injury" without supporting documentation is irresponsible (obviously unless the tell tale signs in an emergency room of dilated pupils and unresponsiveness etc). Unless your husband has been diagnosed by a neurologist with accompanying brain scans and tests this is just a subjective statement that should have never been made. In rereading your recent interaction with him at detox I don't recall seeing a diagnosis at that time of "brain injury" ( if so I apologize for missing it).
What I see is the action and behavior of an addict deep in addiction. Brain injury? Maybe who knows I know that as much as they who have done no testing know.
I don't say that to counter your decisions. Your decision not to deal anymore is the right one. For the 10 - 12 days he was sober I believe you saw what can be. Its unfortunate he did not.
I hope this is bottom for him.
Lots of (((((hugs))))