My boyfriend 4 a year never told me about his ex.He was talking to her all the time & i thought it was work.

my boyfriend who im still dating and planning to get married. He never mentioned about his one ex as they had been working together and i knew this person as his co-worker not his ex. all the time he was talking to her and i thought he was working. he even got married to her by some religious ceremony which he says he didnt know the value of as they are not same nationality.I really dont know what to do. I love him a lot but cant help forget that he kept me in dark. I saw there conversation where she is calling him honey, husband etc , although his response is about work yet he didnt say anything to me about her hurts me. I insisted that why he showed me these conversation, i never spyed on him, never checked his email etc, against my value. I only trust never doubt. Im heartbroken coz i thought he was different and never imagined he would keep me in dark. he says he loves me alot and due to some important work related issue he had to keep in touch with her. also he never told her he was seeing me. his family knows me but she didnt.