Witnessing the self-destruction and suffering by someone you love is one of the most heartbreaking things to face in this life. And naturally you want to help, jump in and save them, pull them out of the drowning cyclone and get them on shore. But with addiction, you can do all of those things over and over again and very often witness them walk right back into that water.
Your husband is correct, you cannot help someone who is unwilling to help themselves. This is where we tend to lose part of our own sanity by continuing to try to change another human being.
This is where al-anon, therapy, and learning as much as you can about alcoholism can be very beneficial to you.