I don't know what your husband was using to self-medicate with, but if it was opiates (that's my son's drug of choice), it can actually reduce symptoms in the short term.
My son picked up that addiction slowly as friends in high school shared their parents pain meds and he helped himself (stole) some from his father's prescriptions. Then, my husband was in a terrible accident and we had bottles of several different types and dosages in the house. It's not like we left them out in the open, but we didn't lock them up at the time.
On opiates, my son seemed symptom free. Then, we found out exactly what was working so well and got him into a suboxone program. He stuck with that for 5/6 years, then this past year, he really went downhill fast. He was also trying to quit the suboxone and finally did - cold turkey. No one can explain how he went from high dosages of that plus Klonopin to absolutely nothing all at once without experiencing any physical withdrawals, but the mental ones were so bad that he ended up in the hospital 3 days later.
If your husband stopped something similar, it can take the brain months to recover just from that.
I truly believe that my son was self-medicating to feel normal more than to get high. I think lots of people with mental illness do.
If you haven't gotten a copy of I'm not sick, I don't need help by Dr Xaviar Amador, you might want to get a copy or check out some of his online videos since you were talking about learning a new approach to things. It's more for people dealing with someone who doesn't have insight (my son had it, now it's gone), but I think it is an eye opener for anyone who needs to learn how to effectively communicate with people. I'm naturally blunt and to the point, so it's a struggle for me to learn what's in the book, but I'm slowly putting it to use.