Hi, I'd like to help you with your question.
There is no where in the Bible that says you must stay in a marriage where you are being abused. God never requires us to expose ourselves to hurt and pain by someone who is abusing us.
Keep in mind, you have made a very good effort to make the marriage work. You went to counseling, stayed with your husband through all the efforts to get treatment, and you have thought this through, including asking for help from others. This is not a quick "you made one mistake" decision.
It is understandable that you would feel guilty. You care about your husband and you married him expecting the best. And the nature of alcoholism creates a dependency and strong emotional pull for the mate that is coping with an abuser. Alcohol abusers can make others feel sorry for them. It's how the abuse works and why so many wives and husbands find it hard to insist that their spouses stop using. Breaking away from the emotions of the situation is difficult and trying.
You may want to consider seeing a therapist yourself. If you found that your original therapy was not effective for you, you can try another therapist. Talk with your doctor about a referral or, if you attend church, your pastor can help. Or you can search on line at http://therapists.psychologytoday.com/rms/.
You can also turn to your church for support, which you may have already done. Talk with your pastor about how you feel. Christians do divorce and if done in cases like yours, there is a justification.
There are also resources you can use at home to help. Here are some to get you started:
Live, Laugh, Love Again: A Christian Woman's Survival Guide to Divorce by Carla Sue Nelson, Connie Wetzell, Michelle Borquez and Rosalind Spinks-Seay
Not Under Bondage: Biblical Divorce for Abuse, Adultery and Desertion by ***** *****
A Woman's Guide to Healing the Heartbreak of Divorce by Rose Sweet
You can find these on Amazon.com or your local library may have them for you.
I hope this has helped you,