Maybe another way to frame this very difficult situation—I’m so sorry that you both are suffering so much—is that he needs the space to embrace and be responsible for his recovery on his own.
One thing I have learned as both daughter and wife to alcoholics, and in recovery from being one myself, is that as long as there is someone to take up, or “share” responsibility for the harm their addiction causes and “help” the addict, they will typically avail themselves of the support no matter what the cost to the loved one offering it.
$85,000,00 is a lot of money. Who will be paying this back? What does this mean to your financial security, lifestyle, and the need to continue working well beyond retirement? Love and care for another person doesn’t mean you have to light yourself on fire to keep them warm. He may indeed get sober for good this time, or it may be serial relapses, and more peripheral addictive relapses like the gambling, for the rest of his life.
Are you ready to accept he may never change? The past, unfortunately, is often the best predictor of the future. Maybe if he didn’t have you to fall back on to try and “fix” the situation, he might very well step up and make the difficult changes he has to. We can’t know what will work—but that work is his to do, and one school of thought is that stepping back and allowing him to find his own way is actually the most respectful and supportive thing you can do for him as an adult man capable of making his choices—including drinking and gambling if that’s what he wants.
Keeping yourself financially and emotionally linked to that, or not, is the only thing you actually have control over. If you legally separate now, there is nothing that says you cannot get back together in a year or two if he makes the changes he needs for you to have peace and freedom. Right now this is a nightmare for you, and isn’t sustainable for the long-term. Only you know, however, what you can accept and how much you are willing to pay from your own Life Energy to (possibly) just assist him in keeping the rollercoaster of his relapses going.
That’s a difficult call. I supported my mother until she died to continue her drinking and smoking. It cost me so much emotionally and physically, and led to a great worsening of my own drinking. Now my spouse drinks, but I have chosen to stay as he has significant health problems and his drinking is more limited in scope and I am not ready to step back yet—financially or emotionally. So I think only you can decide.
I do know that had my spouse run up that kind of debt and relapsed after multiple rehab stays I would certainly not still be living with him and letting him destroy my future retirement and financial freedom. That would be a non-starter, but that’s me and you have to decide how you feel about it—we support you whatever your choice. But put yourself first because he certainly is putting himself first and leaving your to clean up his mess. That’s a hostage situation, and not a healthy relationship.