I Need Help With A Couple In My Quinceanera..

Well i have a couple in my quince and lately i found out that they went way further than kissing, (im trying to keep this G), and now i dont feel comfortable around them at all. No one does. A lot of my friends in my quince and ones that are not dont have no respect for them, not just because they did that, but the way it was approached, not mature. I have heard that this wasnt her first time, before she had her quinceanera, and your suppose to be pure. I think that is very selfish of her to do that. I`m losing my friendship with her, and her boyfriend. I`m also scared that shes pregnant. If she is i really dont know what to do but take her out, if she isnt, im still very uncomfortable about having her as one of my damas. Lately i found out that she told horrible lies about herself to make her look good, and im very mad at the moment. I just dont know what to do. Shes putting more stress on me than i already have because im only 61 days from my quince, and i really dont think friends should do that to other friends. I guess shes really not a good friend anymore. I still need help.