Am I crazy ?

So I been with my fiancé for 2 years . We are 20 weeks pregnant with are son Christon 💙, But I’m always moody even before the pregnancy I bring up his ex constantly. I do it because my daughter dad always cheated on me with his ex it was always something so know that I’m in a whole new relationship I accuse him of his ex from 7+ years ago . Idk why I do it I write girls on his fb , instagram ect to see if something is going on . Am I crazy ? And if I am any advise because I feel like I’m loosing it this man has did nothing to me but comment under a female picture. Goes out his way just to make me happy idk I have this guard up .