Hello and welcome! I am glad you are here, there is good support here.
Thing is, addiction is progressive. He is a long term abuser, which means it will progress. His health will decline and of course you will be left to take care of him. I don't mean to scare you, but that is the reality for so many.
I encourage you to speak to an attorney. I know I spoke with an attorney a year before I actually split from my X. It was free. It also helped me understand what to expect if I left, how we would be able to separate our finances, etc. It helped me to feel much more in control.
Do you have face to face support? Counseling, Naranon, Celebrate Recovery? These are all great options and would likely help you a lot.
There are many here who have shared their experiences, I encourage you to read as much as you can. Take a look at the stickies at the top of the forum, they are full of great info.
Hugs to you. Keep coming back, you are not alone!