Please Help!!!

Okay so me and my child's father been through so much and the trust is really messed up between us ...but we can't seem to get over each other but we put on a act as if we don't care what the other does or who they talk to but wen we actually start entertaining someone else he get super jealous or I get mad because we obviously don't want nobody but each other but long story short.......whats the right way to ask him to open up and be real about the way he feel about me? or what should I start doing to make him realize the way we act need to stop??