My heart goes out to you. I've been where you are, I chose to leave. First and foremost, stay safe...if you and your children are not in a safe environment, then leave.
I made my decision after I read "Co-Dependent No More" by Melody Beattie. After all the hype of codependency came out, a lot of true co-dependents problems were minimized. I realize that we all have some type of dysfunction and co-dependency in our lives.
You are faced with a problem that will effect you and your children for the REST OF YOUR LIFE.
Your question about placing some boundaries on the alcoholic in your life.........will it help? Will it make a difference? No....probably not.
Stop immediately trying to change temporary circumstances and start changing yourself. You'll never be able to change him. Never.