What do you do when your husband does not want to reveal his past marriage ?

My husband and I have been married for one month so far. During the course of our courtship, I have been asking questions about his past. He changes topics on me and does not want to talk about it. He has been married before for eight years and has three children with ex-wife. When I asked him what had ended their marriage he said that she accused him of having an affair. He swore to me that he did not and made it look like she was being delusional. I also asked him about how many people he had dated before he met me. He told me two one of each never been intimate with. What bothers me is ? Last night we started talking about this and he gave me a different story. I kind of yzed and added two and two together. I then questioned about the duration of each relationship. He told me that he was still married to his ex-wife when he kissed one of the other girls. He told me that she had that they were seperated that she came after him. What disturbs me the most is he did not mention this to me before when he told me that they were just friends and then kissed one night and nothing happened. I pressed on more questions. he started changing the topic and tried to distract me with kissing. I refused it and got on him face. I told him that I deserve honesty and that I'm his wife. I told him that I will not judge him for his past but I need answers. He would not still tell me. I also gave him an ultimatum about if I found out that he lied to me and I will. I will end the marriage because he lied to me and one thing I can never stand up is a lie. I told him this and he was mad with me about it. I can not believe him. I told him eveything about me and about my past. Why can't he not tell me? What is it that he hiding from me? Do you guys think that there is something about this my husband? or am I being paranoid for no reason. Help me out here