I'm a lad of 18 .. i love a girl n she is of my college only . she used to sit with me in my exams(though it?

went well) . i was quite hesitating to talk to her and even thought to ask her phone no but i was scared of its results . she also responded to me well . But after the exams were over I lost contact with her . then i came to hear from a friend that a boy was flirting her and she is almost in his traps . the boy is a duffer and ill mannered. and the the girl is nice n simple and has slightly less knowledge and i think as it was her first time she compensated with anyone(with that idiot) . What should i do now ??????