Yes, it is possible to get pregnant from pre ejaculate. Your friend needs a pregnancy test. There must be some ***** somewhere you can talk to. If your school nurse is so ******** as to refuse your friend and call her a name, you need to look elsewhere for help. If your parents or your friend's parents can't help (which is who I would go to first, to be honest), is there a teacher you trust? A school counselor? Your principal?
If for whatever reason it's not possible to ask an *****, take a city bus to a drugstore or a planned parenthood to get a pregnancy test. I strongly recommend planned parenthood, because in addition to giving your friend a free pregnancy test, a counselor can give you good advice and accurate information to protect yourself (and your friend) from pregnancy and STD's.