girl in waiting? hmmm what should I do?

I am having sex and the greatest friendship I have had with a women, this has been going on for at least five months. I have known most of that time that she has never really had a relationship with anyone, tried once with women and she was young; her parents put in end to it with the use of law enforcement stuff. She has talked with and online dated men and had a few flings (sex nothing more than) with women. Now here we are, she has an online guy friend (known of him about five years) and they are suppose to meet up and see what happens as far as if he should move from his state to her state and be in a relationship (given him the relationship bc she is more into men and has known of him longer, but never met him yet)... which she nor I really think will happen but it is one of those things that we know needs to happen or else wonder what if kind of stuff... I have been honest with her that I don't think I could get over her being with him for nine days, and then she comes back to me. I don't think I can handle that, I think I won't be able to have sex with her again, should I try I guess is my question? We both feel amazing chemistry but she is afraid to be in a relationship especially with a woman (me). We are so great together, I am afraid her meeting this guy will ruin it, but I know she has too... do u think I should try to get over the fact that she will have sex with this guy and then b with me, or should I try to keep the friendship (don't think she could handle just friends) in tact? P.S. We are both pretty sure, but nothing is ever fool proof that this guy is a safe kind of meet. I know she is more str8 than lesbian (she says bi with more str8 tendencies, but I say pansexual-she is more into emotional bonds when u hear the whole story), and I already have told her I love her and that I am in love with her... she too has told me that she loves me and is in love with me, her confusion is only that she has been intimately talking with this guy for such a long time, she doesn't want to lose either of us, but I have made it clear and so has he that she can not be with both of us.. he does not know really about me, he has though made it clear he wants to be exclusive if the meeting goes well. I am unwilling to share as well, so what do I do? b patient and see what happens or do I stop the whole thing. I really don't want to stop the friendship but I don't think she can handle just being friends, she already has been flippin out at the thought of me with someone else. IDK what to do... I posted this question early today, just looking for more advice and thought I would clear up of few things.. thanks for ur thoughts.