Abb, I understand your concerns. I’ve been in some such situations.
First, I suggest that you look at what a good Catholic girl she is. Don’t let evil thoughts get their way. And give her the benefit of doubt. There’s probably a good explanation for everything and even if she’s done something not exactly plausible, there’s probably an explanation for that which makes it looks less bad because it’s a weakness and not malice.
Consider that she’s been open with you to the point of letting you use her computer to check your mail, telling you what’s hers is yours etc. Okay, friends let you use their computers too, but this girl practically left her secrets all open before you so far as they were on the hard drive.
I would ask her, maybe not confront her, but ask her. You need to know and you deserve to know. Until she tells you, you don’t know anything concrete, so you don’t need to presume anything (or it will likely prove false). Just ask her. Until she tells you - presume the best for her, try not to draw too many conclusions.
If there is a direct contradiction between what she said to you early and what she wrote in that document, then you may want to let her know that and see how she explains it. All of us can be caught with a “direct” contradiction over a time long enough, with a large enough number of conversation to draw information from.
See… Perhaps she had two boyfriends and the third guy wasn’t a boyfriend? Maybe they had some relationship but it didn’t have the name or status of a boyfriend-girlfriend relationship? Or maybe they had no relationship, they were simply in love? In fact, it’s even possible that her definitions changed or that they were different in each conversation she had. This is rare, but sometimes it happens. A real direct contradiction would be something like, “I don’t know that guy,” contrasted with, “I loved him and we were a couple,” or, “I’ve had two boyfriends,” and, “I’ve had three boyfriends.” These are very clear contradictions. Telling you that she has had two boyfriends and then writing about some other guy she loved is not yet a direct contradiction. Perhaps there are some omissions, some lack of clarity, some confusion, some genuine mistake, some inconsistency, maybe a contradiction, but not really a direct contradiction of the kind I described above, comparable to contradiction in a clear yes/no matter. She has some explaining to do, but this doesn’t mean she’s lying.
Also, even if she has actually lied to you, her reaction afterwards is still important. People have different weaknesses. Some people lie but are good people. Some people never lie but often do worse things. Besides, do you prefer people who lie because they don’t want to hurt someone’s feelings or because they’re afraid, or people who never lie because they are too arrogant and they don’t care what others think or feel?
If it turns out there’s a game being played, I would run. However, it doesn’t seem likely in your case. I think the girl just got lost in her feelings and confused. Perhaps she said some things which weren’t exactly truthful and now she’s struggling with setting it right. I would be inclined to see it as just a weakness, maybe even a singular one, if she were genuinely sorry and if it were obvious she loved you. Conscious, repeat lies which are aimed at manipulating you and getting things from you or making you behave in some way, that’s another story. From that you need to run. But as I said - that seems unlikely in your case. Habitual lying also seems unlikely in this case.
This comes from someone who has experienced a lot of lie.