I can't believe you don't want to walk away. You surely can't think that you deserve this treatment. All the time he has been able to get away with his awful behaviour, you have been enabling it. You're even suggesting he may be unable to help his disgraceful behaviour. Face it, he's probably just a horrible person and you shouldn't want any part of life with him any longer. If you're not there, he can't abuse you. Stop trying to fix something that must be - after 30 years - unfixable. Counselling for him would only work if he wanted to repair your marriage. He doesn't, so it's rather like telling him he's going to give up smoking. He's not, until HE decides to.
Tell your children, stop covering up, stop wishing things were different - make them different, stop allowing yourself to be treated so badly and GO. See a Solicitor, take proper advice, and find somewhere to live.
Tell yourself you deserve so much more and grab the rest of your life and live it, surrounded by people who care for you. I would - it seems that everyone on here would. We can't all be wrong and we're wishing hard for you to have a happy life!