Can you go to a parent's place or a friend's? Talk to him (without malice) and calmly explain to him that you can no longer be a part of his addiction. If he wants to stay together, he needs to make an honest and sincere effort. You're afraid that you're a part of his problem and you can't nurture y'all relationship if you can't take care of yourself. It's like what all the family members say on Intervention. "I love you but your addiction has effected me negatively in the following ways..." you don't really need to tell him how it's effected him. He already knows that. Since your children are grown, maybe they'll participate as well. He must realize that there are consequences. Don't say anything you don't plan on following through with. Be honest with yourself as well. Are you really willing to leave? Do you really want to cut off all ties with him? You must do whhat is right and healthy for you because if you are hurting and worrying all the time and in pain, how can you support him. There is no easy answer to this and it's a terribly hard thing to do. Has he gone to rehab? Is he willing to go (first time or again)? Will he go to meetings? Get a sponsor? You've been fighting this battle for years. It's time he joined it.
(I watch way too much Intervention!)