Run. You are not married. You are not required to stay with him or help him.
I know this sounds harsh. I say it as a Bipolar person who has run a forum for Bipolar people for 10 years. We sometimes have the loved ones of Bipolar people show up and we tell them the following:
1. Tell him if he does not see a doctor and get a solid diagnosis, you are out of there.
2. When he gets the diagnosis, tell him if he does not comply with treatment 100%, you are out of there.
Relationships go two ways. If he is not willing to do these two things for you, then he puts himself first and you really do have a problem on your hands. I take my meds every day, twice a day. I do it for my husband and my daughter. I do not have extreme Bipolar, yet even so I am committed to staying on top of this illness. He needs to take responsibility for his own life. He needs to decide when enough is enough and he will submit— but you cannot do that for him.
1. Draw a line. It can be a deadline. “If he does not get to a doctor/start treatment by x date, then I have to accept that he is never going to do it.” And then get out.
You are talking about being afraid that he will kill you. KILL YOU. This is not normal, this is not a normal relationship. You cannot save him– you can only save yourself. You deserve someone who loves you and can be stable in that love, dependable. It might be him, who knows, I hope so, but it will only be after he has made up his own mind that his life would be better under treatment than it is right now. “You can lead a horse to water but you can’t make him drink.”