Hi subwife, I'm sorry for what brings you here. I wouldn't tell you that you have to leave, as that's your decision.
Your husband's "reasons" for needing to use sound a lot like my old reasons. I have a stressful, demanding professional career, and chronic severe back pain. I thought I abused alcohol and pain meds for these reasons. Now that I'm sober a few years, I know that I drank and used because I was addicted, plain and simple. I still have a demanding career and back pain, but now I find healthy ways to manage these stresses, without alcohol or pills.
You don't have to put up with addiction.