Hello baboo: I haven't posted this in a while.

But I used to know a guy who was fond of saying: "If you want to know which way the bullet is going, look down the barrel of the gun."

If you re-read what you've written here, you'll see what your future is likely to be if you stay with this person.
You wrote your friend will NEVER go to the doctor. Unfortunately professional mental health services are probably what he needs & may be the only thing that will help him. Perhaps in time, he will come to see this himself. But who knows how long that may take or what may have to transpire in order for it to occur? Much as you might wish to you cannot make it happen, in my personal opinion.

So, assuming that this is the case, the question becomes how long are you going to be willing to tolerate the unhappiness your friend causes you? Only you know the answer to that question.

I wish you well...