Make an appointment with a solicitor and dig out and photograph all the financial information you can get hold of, so all debts, loans, mortgage, and all assets, so savings, pensions, benefits, any earnings etc.
Work out what your bills are, and what your income is. This will help you get a grasp on where you need to be in terms of a divorce settlement in order to live independantly of him. As someone else has said, I'd get out now before he becomes even more infirm due to his alcohol abuse, and it puts you in the position of his carer.
Don't hang about to find out what that's like, tomorrow is a new day, call a solicitor and make an appointment to find out what you might be able to expect in a settlement if you divorce him, that's the first step.
Keep all this to yourself, do not tell him, especially if him knowing will make your life difficult.