How to deal with someone with Schizo-affective disorder?

I am dating a guy who has this disease and can not trust me at all because of it. I have a job opportunity and can not take it without him throwing a fit about it because my ex had worked there and he can not come there and check on me. I have never cheated on him or even attempted to. I always show that I want him and no one else when we are out and everything else yet I still am accused of cheating or told that I will cheat if i go somewhere or want to do something that isn't with him. All I want to know is how can I better understand him or work with him without just giving him his own way all the time? Also when we fight he expects me to just be calm no matter what he says or does till he cools off . We have only been dating for a few months and I have a temper of my own that I am working on keeping in check but to basically be told your a when you have done nothing wrong or statements such as "no wonder he broke up with you" It gets a little more than difficult to just sit there and take it. I guess I feel that since I have done nothing wrong I should be able to defend myself without repercussion. If anyone that has it or has lived with someone who has it could give me their input it is much needed and greatly appreciated. kind of felling hopeless.