TG, your thinking is still so "in the box." You view yourself as this helpless girl. When in fact, you already are an independant GROWN adult woman....you need to start changing your dialogue. Who will you fall back on? You'll fall back on yourself. If that fails because you are truly not capable, do you honestly think your parents will let you starve or go homeless? You are making a bigger issue of this safety net than need be. You'll do what you have to do to survive.
People often ask me when I'm out with all the kids, "how do you do it?" I realize they don't get what they're saying. I remember only having one child and thinking it was emotionally taxing, trying and hard. I did it though, you know why? Because I had to. He was my child. It isn't much different now that I have four children, I "do it" because I have to, they are my children. Looking back, I having one child seems like a piece of cake but I know it's all revelant to what you're used too. So having four doesn't discount how hard it is for the mother of just one.
My point to all that is, you will take care of yourself because you have to....end of story. Your fear that paralyzes you takes up way too much of your time.
About whether or not your ah is serious? who knows....you don't, we don't, he doesn't but why does his declarition of "I'm done now" mean a halt to your plans. You're like me, I used to wait for this "big episode" to happen to move on. I wanted something big to happen so I could leave and be right, it wouldn't be my fault, I wouldn't have guilt, etc. You know what? The big things kept coming and I did the same as I always did, as you do, I'd stand there and listen to his lies, believe him and BAM, I was stuck again. A big thing isn't what will make you leave, it isn't any easier during an episode. You aren't more equipped to handle it just because he did/does something really shitt y.
So is he done drinking? who knows and it shouldn't matter.