Welcome! I hope you find this place as helpful as I have.
You might want to try AlAnon meetings. Many in here find they provide the suppor tthey need.
I understand your feeling that leaving him would be abandoning him BUT he is an adult, responsible for himself. You are not responsible for his choices and behaviors. He can choose to deal with his issues, whatever they may be. Or not. Either way its out of your control.
You can choose to educate yourself on alcoholism and codependency (which many of us in here have found is our particular problem), you can learn how to make your decisions based on who your AH is rather than who you hope/wish/think he can be, you can learn to understand what your choices are and act on those choices as you think is best for you.