I feel my husband is cheating..what to do?

First of all I'd like to say what u all will be thinkin anyway...I am in a very weird and dysfunctional marriage. But I am a very religious person and I don't believe in divorce unless someone has committed adultery. Me and him got evicted and so we don't live together. Me and him fight all the time. He hurts me alot even though he says he doesn't intentionally. But we always talk about our relationship. But lately he has been overly irritated and cruel to me. I just had our son 4 weeks ago and things were fine but now he is acting like he don't care to even be with me. He doesn't even call me at all and I am trapped in the house trying to recover so it would be nice for him to call and it hurts me that he don't so i tried to tell him he really hurts me sometimes even though he don't mean to. Instead of acting like he cares he snapped on me saying that I am selfish and only care about me and repeatedly hanging up on me. I get this feeling he is cheating down in my gut but there is no reason for me to feel this way. Her hurt me so bad and he hung up on me i kept trying to call him and he wouldn't answer so I text him an said it's over and I haven't heard from him since. It ain;t like him he usually tries to work things out. Why is he acting like this? know this was poorly written and even confusing...But why do I have this strong feeling that he is cheating on me!