gh, the first question you should ask yourself is this: what is my boundry in regaurds to om? will i continue to allow her to talk to him or see him? if not then dont lie to her, tell her you know she has contacted him, that you dont know what is going on but you need to know, that she has to be totally honest with you. you dont have to tell her how you know, that you just know, let her figure it out herself as of why you know. i do think you need to have this conversation with her today, right now, before she goes to where ever she is going. unless you are confortabul with her still in contact with him. which i dont think you are, so confront her let her know you know, and ask whats up with it. do it now, right now
