I think it all comes down to whether we think alcoholism is disease or not.
Before I trully understood it is disease, I used to think all kind of things, and I was so resentful. BUt once I truly understood in my heart that alcoholism is a terrible disease I was able to let go of my resentment. It didn't take away the pain, though, as I still feel it, but I also feel the empathy. Do I chose to live with an A or not is a completely different subject. It is my own choice to decide what I want in my life, but it doens't remove the empathy I feel for A people. To be honest, I think their struggle is worse than mine, as I do have a choice and they don't so much or at least it is much harder.
I think at the end of the day, we are all just people, different people, what is simple for you can be hard for me and vise versa, and we all struggle. I'm an ACOA too, and I've been struggling with resentment for years too, I think the way to get over it is to understand alcoholism is a disease, to take the reality for what it is, and to work on our expectations of ourselves and others.
Also I think anger and resentment can be good to get you to start moving, acting, but it can be dangerous if you stay stuck in it, as it is only working against you.