Your spouse may be in denial about your alcoholism. It happens. She doesn't want to be "associated" with someone who is an alcoholic and your going to AA reinforces that for her. She may see it as a reflection on her and isn't comfortable with that. I'll bet she's thinking about her past marriage and not wanting to go through the same thing again with you. I'm sure it's scary for her, as GirlFromGo said.
The priority right now is YOU. YOU know you have a problem and you are taking steps to get better. That's all that matters. If you don't get sober, your marriage is not going to be healthy anyway, so do what you have to do to prevent things from going that route. The only person who can decide that you are an alcoholic is YOU. And if you have decided that that's what you are, then you have the responsibility to do something about it. Thankfully, you are. My prayer is that your wife will see it too and be grateful that you are taking steps to preserve your life, your life with her, and your marriage.
Follow your heart, my friend. You are doing what you need to do for yourself, which in turn will be a huge positive for your marriage and all of your other relationships. Give her time to let it all sink in and for her to see the positive changes in you that are going to happen. Hopefully, in time, she will see that you knew what you were doing. Best of luck to you.