I have a little experience with bipolar...my daughter is diagnosed and medicated.
It sounds to me like your H does have some mental issues...and bipolar is not generally misdiagnosed. My daughter stayed in denial for many years, and thankfully her husband waited. But she used the same excuse, that the diagnosis was wrong. It was after he did leave her, briefly, that she knew something was wrong.
What would you like to see happen? I can tell you this, if he is in fact bipolar, nothing you will do will make him realize this. It is something he will have to realize on his own. He will need to take the initiative to change it.
Think carefully about what you want to do. And fyi, the time you were together means nothing. I was married for under two years.
Also, this is not something that will be cured overnight. If you choose to stand and fight, it could take years. You will need to determine whether it is worth the fight. I have been at this longer than I was actually married and living with my H...
Im still standin better than I ever did looking like a true survivor feeling like a little kid Im still standin after all this time and Im picking up the pieces of my life without you on my mind..