That's pretty much what my AXH said, too -- especially the "if I had cancer, would you leave me?"
My response to that was "if you had cancer and were undergoing the recommended treatment, I would not leave you because of the fact that you have cancer. If you had cancer and were undergoing treatment and behaved like at complete ass toward me, I would leave you because you behaved like a complete ass.
The thing is, you are not seeking the recommended treatment for your disease. You are getting sicker, and meaner, and your behavior toward me is unacceptable, regardless of what the reason for it is."
I never said that, however. Because most alcoholics can't be reasoned with while they're actively drinking.
So my advice would be to not respond to that. Because you'll probably just get more of the same. You can't win.