Would I be crazy to stick by my fiance` through all of this?

When we first met he liked me completely for who I was. He liked everything about me. He even tried to end our friendship, saying it was too hard to just be friends (I was with someone else) After my breakup he was there for me. We were bestfriends, spent so much time together he felt like my other half. We literally finished each others sentences. I waited a bit to get w/him because he was too special to be a rebound. He would be able to look at me & know if something was wrong, would beg for me to talk to him about it. I had some mental issues. Every little thing he said or did would set me off & I would act horribly. We moved in together after a while. I treated him badly by being so hard on him for over a year. He became cold toward my feelings, began lying in fear of how I would act. After that I got help, was put on meds. It made me completely self-aware, I was improved so much. For a month things were great, he was caring again. But then turned cold again. When I would share my feelings or be angry because he told a small lie he would get furious, say horrible things to me & put the blame on me. I literally couldn't even say 'hey can I talk to you' He even smacked my arm once when I simply asked if he lied. I know how it sounds but I can tell its also unresolved mental issues. One moment he realizes & cries out of guilt & then another hes a different person. He seems to have a bipolar disorder. Would it be crazy for me to wait for him to get help like he did for me?