make himself dependant on me
You know this, but he point of a divorce is that he would not be able to make himself dependant on you. You would live seperately, physically, financially, and emotionally, and it sounds like it's the last one that might be the sticking point for you.
I fully understand that thirty years is a long long time, but you need to stop fulfilling that dependable mother role, in order to break this naughty child cycle you're in. You sound like you're in a good position to be able to access the therapy that you might need to untangle yourself from this relationship and move on.
In practical terms, get a hold of all of the financial information relevant, ie mortgage, name on the deeds, bank statements, earnings, any savings and pension information plus basic outgoings. See a solicitor, and find out what the financial position is likely to be if you divorce, and start proceedings.
If you are scared of what he will do, then rent somewhere for you and the kids, and then tell him you want a divorce. Tell the kids. Tell your friends and family. And then step through the motions with your solicitor. It's not pleasant, and you will need resolve to get through it, so get really clear why you're doing it, starting with a belief and sure knowledge that his behaviour is nothing to do with you, and not your mess to stick around and clear up.
What he does after you leave in terms of quitting his job, not going out of the house for days, eating mouldy baked beans from the can, drinking and smoking himself into a mineral state shouldn't be on your list of things to think about.