Jo,
You sound like an amazing Momma!! What you have accomplished over the last few years all by yourself, you need to pat yourself on the back. Talk about tough, and you survived!! Not even breast cancer can get you down.
The question is how can you rebuild. You are doing just that, you are not to make ah (alcoholic husband) a priority in your life anymore, thats over. The kids and you are number one. Your older kids are able to hit a alateen meeting and you can go to an alanon meeting. These meetings can really help. Read all over this forum and educate yourself about addiction. Education is power.
Learn not to engage with him when he is drinking. If he wants to fight take the kids and leave the house. They do not have to witness this and a neither do you. If you can't get out, call the cops and just ask him to be removed. Just remember when you threaten something you have to follow through, if you aren't going to do something, don't say it.
Keep asking questions, my friend!! You are a brave women and good for you for wanting a better life for you and your kids. You Deserve it!!