I don't post much around here anymore, but your post really struck a chord with me. I think I could have written it about a year ago. The short answer to your question, in my opinion, is yes, we are equally to blame.
But, what good does blaming do? Blame him, blame yourself, blame the weather, the location, the companies that sell the alcohol, his parents, your parents, the political party in office--see what I mean?
The positive I see in your post is that you are aware that you play a part in this dysfunctional relationship. I know it doesn't feel positive, but really it is. Once you are aware that you are part of it, you can change it. You can recognize your choices, and you can do something about it. You don't have to be a victim of the circumstances. You don't have to live your life at the mercy of his actions.
Good for you for being aware and willing to learn. I can't remember the exact quote, but there is one that goes something like this: "We did the best we could with what we knew, and now that we know better, we can do better."
I probably mangled that, but you get the idea. Blaming yourself does no good, learning to do better will change your life.
L