Im mad at my girl, but should i be? what should i do about what happened?

shes always doing things that shes knows ill get mad at, and she knows that if i did the things that she did, she would get mad too. ok so last night she ended up talking to a guy on the fone untill 5:30 in the mornin. she knows this guy likes her, he hitts on her, and she told him where she lived. they even talked bout ual stuff. how should i react? what should i do? how should i feel bout this?