my fiance think im crazy

well one Saturday I sitting on my couch and I heard a girl laughing in my kitchen but it sounded like a flirty laugh. so I asked my fiance who that was so he said it was someone on a game that he plays . I let it go well on the Monday he was going to okay football as um on the computer which is mine I see a message so I clicked it and saw a bunch of voice messages from both so I listen a few were about the game . but then u hear him telling her that he left work and explains what he was doing that night . meanwhile when I looked at the time he had messaged her before me and one time at work during break . this girl is from Australia. so then I hear her tell him " hey I'd like to get to know you better what do think? I flipped called him and told to not come home . he said he didn't did anything so no come home and we can hear this together. he said I did nothing wrong and I said my name was not any Convo and he said she know about u and I said well she is a bitch then . so he messaged her saying he could not talk to her . where she turns around and says . well if I was in a relationship I would trust my man and not snoop in his business and for weeks he would say if you wanna talk just talk about game . then she had the nerve to ask him to get the whatsapp on his phone so I could not see their convo . I'm like do u not see this what she is doing trying to start crap first off then being sneaky. no class