I am so sorry for what you are going through.
I can tell you from experience that you need to save yourself and let him go. He is spiraling out of control and taking you down with him. You can't save him no matter what you do. (Trust me, I tried for 3 years to save my fiancee and am still paying the price.)
Go to therapy. Use your family and friends for support. Keep posting here. Find a support group. Try to eat and sleep.
You Will get through this