Awkward situation with friend/ex
I am 21, the girl is 19. Her and I dated for about a month nearly a year ago. She had just gotten out of a relationship, and our dating ended because she still felt something for her ex. They broke up once again shortly after they tried to reconcile, but that's irrelevant to the issue I'm wondering about.
Her and I have stayed friends this entire time (we've been good friends for about a year now, in fact she's probably my best friend, and vise versa). She's had two short things with a couple of random guys, nothing serious at all; same with me.
About a month ago she started talking with a guy online out of state. They seem to have a good connection, as they talk all the time. She is going out to meet him shortly, who knows what's going to happen there.
The twist is her and I have been getting pretty close the last 3 or 4 weeks. We've had sex multiple times, stayed at each others house quite a few nights, spent a lot of time together (basically everything two people in a good romantic relationship would be doing). Things have just been happening, and it's all seemed natural. We both love each other as friends pretty deeply, but I am feeling much more than that now. I haven't told her, but I believe she knows.
She's said some pretty heavy things; things that would make me believe she wants to be in something lasting with me. She feels guilty, though. Guilty that she's done things with me, and now she's going to visit this guy and she is feeling guilty about doing this to me. I would imagine she's confused (but are woman ever REALLY confused? ;) )
I don't know how to confront this... I definitely don't want to give any ultimatums to her, as that could be pretty drastic on our friendship. Any advice? :)