My stupid boyfriend flirts with girls through his PS3?

Alrighty so one of my friends told me how my boyfriend was bragging one day(when i wasnt there) about how he can talk to girls through his PS3. He said it right after he told my friend about how he goes through my phone to make sure im not cheating. So my friend was like okay your worried about her cheating when your talking about how you can talk to girls through your PS3 ha and he told her to shut up. And just right now i heard some girls voice and hes play GTA on his Playstation and i heared him asking for her name and telling her to get in his car. And i guess she got in back and he goes "what you getting in the back for you get to sit up front". This may not sound like much but i think its disrespectful to be flirting with girls. So i went in there and told him what i heared and said were you just talking to a girl and he said ya so what. Then started saying how im stupid its just a game. Game or not flirting with other girls is still flirting. And he got all mad at me. But i dont care. If i did that he would kick my ***. Ya im pissed and i dont exactly know how to handle it. If someone could please give your kind advice or opinion i would love that<3 Thank you:)